diff --git a/src/accounting/__init__.py b/src/accounting/__init__.py
index 390ce9c..9dfed9b 100644
--- a/src/accounting/__init__.py
+++ b/src/accounting/__init__.py
@@ -63,6 +63,9 @@ def init_app(app: Flask, user_utils: AbstractUserUtils,
     from . import account
     account.init_app(app, bp)
 
+    from . import currency
+    currency.init_app(app, bp)
+
     from .utils.next_url import append_next, inherit_next, or_next
     bp.add_app_template_filter(append_next, "append_next")
     bp.add_app_template_filter(inherit_next, "inherit_next")
diff --git a/src/accounting/currency/__init__.py b/src/accounting/currency/__init__.py
new file mode 100644
index 0000000..50407ff
--- /dev/null
+++ b/src/accounting/currency/__init__.py
@@ -0,0 +1,38 @@
+# The Mia! Accounting Flask Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The currency management.
+
+"""
+from flask import Flask, Blueprint
+
+
+def init_app(app: Flask, bp: Blueprint) -> None:
+    """Initialize the application.
+
+    :param bp: The blueprint of the accounting application.
+    :param app: The Flask application.
+    :return: None.
+    """
+    from .converters import CurrencyConverter
+    app.url_map.converters["currency"] = CurrencyConverter
+
+    from .views import bp as currency_bp, api_bp as currency_api_bp
+    bp.register_blueprint(currency_bp, url_prefix="/currencies")
+    bp.register_blueprint(currency_api_bp, url_prefix="/api/currencies")
+
+    from .commands import init_currencies_command
+    app.cli.add_command(init_currencies_command)
diff --git a/src/accounting/currency/commands.py b/src/accounting/currency/commands.py
new file mode 100644
index 0000000..e3321f6
--- /dev/null
+++ b/src/accounting/currency/commands.py
@@ -0,0 +1,78 @@
+# The Mia! Accounting Flask Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The console commands for the currency management.
+
+"""
+import os
+
+import click
+from flask.cli import with_appcontext
+
+from accounting.database import db
+from accounting.models import Currency, CurrencyL10n
+from accounting.utils.user import has_user, get_user_pk
+
+CurrencyData = tuple[str, str, str, str]
+
+
+def __validate_username(ctx: click.core.Context, param: click.core.Option,
+                        value: str) -> str:
+    """Validates the username for the click console command.
+
+    :param ctx: The console command context.
+    :param param: The console command option.
+    :param value: The username.
+    :raise click.BadParameter: When validation fails.
+    :return: The username.
+    """
+    value = value.strip()
+    if value == "":
+        raise click.BadParameter("Username empty.")
+    if not has_user(value):
+        raise click.BadParameter(f"User {value} does not exist.")
+    return value
+
+
+@click.command("accounting-init-currencies")
+@click.option("-u", "--username", metavar="USERNAME", prompt=True,
+              help="The username.", callback=__validate_username,
+              default=lambda: os.getlogin())
+@with_appcontext
+def init_currencies_command(username: str) -> None:
+    """Initializes the currencies."""
+    data: list[CurrencyData] = [
+        ("TWD", "New Taiwan dollar", "新臺幣", "新台币"),
+        ("USD", "United States dollar", "美元", "美元"),
+    ]
+    creator_pk: int = get_user_pk(username)
+    existing: list[Currency] = Currency.query.all()
+    existing_code: set[str] = {x.code for x in existing}
+    to_add: list[CurrencyData] = [x for x in data if x[0] not in existing_code]
+    if len(to_add) == 0:
+        click.echo("No more currency to add.")
+        return
+
+    db.session.bulk_save_objects(
+        [Currency(code=x[0], name_l10n=x[1],
+                  created_by_id=creator_pk, updated_by_id=creator_pk)
+         for x in data])
+    db.session.bulk_save_objects(
+        [CurrencyL10n(currency_code=x[0], locale=y[0], name=y[1])
+         for x in data for y in (("zh_Hant", x[2]), ("zh_Hans", x[3]))])
+    db.session.commit()
+
+    click.echo(F"{len(to_add)} added.  Currencies initialized.")
diff --git a/src/accounting/currency/converters.py b/src/accounting/currency/converters.py
new file mode 100644
index 0000000..d696b65
--- /dev/null
+++ b/src/accounting/currency/converters.py
@@ -0,0 +1,48 @@
+# The Mia! Accounting Flask Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The path converters for the currency management.
+
+"""
+from flask import abort
+from werkzeug.routing import BaseConverter
+
+from accounting.database import db
+from accounting.models import Currency
+
+
+class CurrencyConverter(BaseConverter):
+    """The currency converter to convert the currency code and to the
+    corresponding currency in the routes."""
+
+    def to_python(self, value: str) -> Currency:
+        """Converts a currency code to a currency.
+
+        :param value: The currency code.
+        :return: The corresponding currency.
+        """
+        currency: Currency | None = db.session.get(Currency, value)
+        if currency is None:
+            abort(404)
+        return currency
+
+    def to_url(self, value: Currency) -> str:
+        """Converts a currency to its code.
+
+        :param value: The currency.
+        :return: The code.
+        """
+        return value.code
diff --git a/src/accounting/currency/forms.py b/src/accounting/currency/forms.py
new file mode 100644
index 0000000..f8cbff0
--- /dev/null
+++ b/src/accounting/currency/forms.py
@@ -0,0 +1,93 @@
+# The Mia! Accounting Flask Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The forms for the currency management.
+
+"""
+from __future__ import annotations
+
+import sqlalchemy as sa
+from flask_wtf import FlaskForm
+from wtforms import StringField, ValidationError
+from wtforms.validators import DataRequired, Regexp, NoneOf
+
+from accounting.database import db
+from accounting.locale import lazy_gettext
+from accounting.models import Currency
+from accounting.utils.strip_text import strip_text
+from accounting.utils.user import get_current_user_pk
+
+
+class CurrencyForm(FlaskForm):
+    """The form to create or edit a currency."""
+    CODE_BLOCKLIST: list[str] = ["create", "store", "exists-code"]
+    """The reserved codes that are not available."""
+
+    class CodeUnique:
+        """The validator to check if the code is unique."""
+        def __call__(self, form: CurrencyForm, field: StringField) -> None:
+            if field.data == "":
+                return
+            if form.obj_code is not None and form.obj_code == field.data:
+                return
+            if db.session.get(Currency, field.data) is not None:
+                raise ValidationError(lazy_gettext(
+                    "Code conflicts with another currency."))
+
+    code = StringField(
+        filters=[strip_text],
+        validators=[DataRequired(lazy_gettext("Please fill in the code.")),
+                    Regexp(r"^[A-Z]{3}$",
+                           message=lazy_gettext(
+                               "Code can only be composed of 3 upper-cased"
+                               " letters.")),
+                    NoneOf(CODE_BLOCKLIST, message=lazy_gettext(
+                        "This code is not available.")),
+                    CodeUnique()])
+    """The code.  It may not conflict with another currency."""
+    name = StringField(
+        filters=[strip_text],
+        validators=[DataRequired(lazy_gettext("Please fill in the name."))])
+    """The name."""
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.obj_code: str | None = None
+        """The current code of the currency, or None when adding a new
+        currency."""
+
+    def populate_obj(self, obj: Currency) -> None:
+        """Populates the form data into a currency object.
+
+        :param obj: The currency object.
+        :return: None.
+        """
+        is_new: bool = obj.code is None
+        obj.code = self.code.data
+        obj.name = self.name.data
+        if is_new:
+            current_user_pk: int = get_current_user_pk()
+            obj.created_by_id = current_user_pk
+            obj.updated_by_id = current_user_pk
+
+    def post_update(self, obj) -> None:
+        """The post-processing after the update.
+
+        :return: None
+        """
+        current_user_pk: int = get_current_user_pk()
+        obj.updated_by_id = current_user_pk
+        obj.updated_at = sa.func.now()
diff --git a/src/accounting/currency/query.py b/src/accounting/currency/query.py
new file mode 100644
index 0000000..4321f07
--- /dev/null
+++ b/src/accounting/currency/query.py
@@ -0,0 +1,44 @@
+# The Mia! Accounting Flask Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The currency query.
+
+"""
+import sqlalchemy as sa
+from flask import request
+
+from accounting.models import Currency, CurrencyL10n
+from accounting.utils.query import parse_query_keywords
+
+
+def get_currency_query() -> list[Currency]:
+    """Returns the base accounts, optionally filtered by the query.
+
+    :return: The base accounts.
+    """
+    keywords: list[str] = parse_query_keywords(request.args.get("q"))
+    if len(keywords) == 0:
+        return Currency.query.order_by(Currency.code).all()
+    conditions: list[sa.BinaryExpression] = []
+    for k in keywords:
+        l10n: list[CurrencyL10n] = CurrencyL10n.query\
+            .filter(CurrencyL10n.name.contains(k)).all()
+        l10n_matches: set[str] = {x.account_code for x in l10n}
+        conditions.append(sa.or_(Currency.code.contains(k),
+                                 Currency.name_l10n.contains(k),
+                                 Currency.code.in_(l10n_matches)))
+    return Currency.query.filter(*conditions)\
+        .order_by(Currency.code).all()
diff --git a/src/accounting/currency/views.py b/src/accounting/currency/views.py
new file mode 100644
index 0000000..ba76169
--- /dev/null
+++ b/src/accounting/currency/views.py
@@ -0,0 +1,178 @@
+# The Mia! Accounting Flask Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/6
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The views for the currency management.
+
+"""
+from urllib.parse import urlencode, parse_qsl
+
+from flask import Blueprint, render_template, redirect, session, request, \
+    flash, url_for
+from werkzeug.datastructures import ImmutableMultiDict
+
+from accounting.database import db
+from accounting.locale import lazy_gettext
+from accounting.models import Currency
+from accounting.utils.next_url import inherit_next, or_next
+from accounting.utils.pagination import Pagination
+from accounting.utils.permission import has_permission, can_view, can_edit
+from .forms import CurrencyForm
+
+bp: Blueprint = Blueprint("currency", __name__)
+"""The view blueprint for the currency management."""
+api_bp: Blueprint = Blueprint("currency-api", __name__)
+"""The view blueprint for the currency management API."""
+
+
+@bp.get("", endpoint="list")
+@has_permission(can_view)
+def list_currencies() -> str:
+    """Lists the currencies.
+
+    :return: The currency list.
+    """
+    from .query import get_currency_query
+    currencies: list[Currency] = get_currency_query()
+    pagination: Pagination = Pagination[Currency](currencies)
+    return render_template("accounting/currency/list.html",
+                           list=pagination.list, pagination=pagination)
+
+
+@bp.get("/create", endpoint="create")
+@has_permission(can_edit)
+def show_add_currency_form() -> str:
+    """Shows the form to add a currency.
+
+    :return: The form to add a currency.
+    """
+    if "form" in session:
+        form = CurrencyForm(ImmutableMultiDict(parse_qsl(session["form"])))
+        del session["form"]
+        form.validate()
+    else:
+        form = CurrencyForm()
+    return render_template("accounting/currency/create.html",
+                           form=form)
+
+
+@bp.post("/store", endpoint="store")
+@has_permission(can_edit)
+def add_currency() -> redirect:
+    """Adds a currency.
+
+    :return: The redirection to the currency detail on success, or the currency
+        creation form on error.
+    """
+    form = CurrencyForm(request.form)
+    if not form.validate():
+        for key in form.errors:
+            for error in form.errors[key]:
+                flash(error, "error")
+        session["form"] = urlencode(list(request.form.items()))
+        return redirect(inherit_next(url_for("accounting.currency.create")))
+    currency: Currency = Currency()
+    form.populate_obj(currency)
+    db.session.add(currency)
+    db.session.commit()
+    flash(lazy_gettext("The currency is added successfully"), "success")
+    return redirect(inherit_next(url_for("accounting.currency.detail",
+                                         currency=currency)))
+
+
+@bp.get("/<currency:currency>", endpoint="detail")
+@has_permission(can_view)
+def show_currency_detail(currency: Currency) -> str:
+    """Shows the currency detail.
+
+    :param currency: The currency.
+    :return: The detail.
+    """
+    return render_template("accounting/currency/detail.html", obj=currency)
+
+
+@bp.get("/<currency:currency>/edit", endpoint="edit")
+@has_permission(can_edit)
+def show_currency_edit_form(currency: Currency) -> str:
+    """Shows the form to edit a currency.
+
+    :param currency: The currency.
+    :return: The form to edit the currency.
+    """
+    form: CurrencyForm
+    if "form" in session:
+        form = CurrencyForm(ImmutableMultiDict(parse_qsl(session["form"])))
+        del session["form"]
+        form.validate()
+    else:
+        form = CurrencyForm(obj=currency)
+    return render_template("accounting/currency/edit.html",
+                           currency=currency, form=form)
+
+
+@bp.post("/<currency:currency>/update", endpoint="update")
+@has_permission(can_edit)
+def update_currency(currency: Currency) -> redirect:
+    """Updates a currency.
+
+    :param currency: The currency.
+    :return: The redirection to the currency detail on success, or the currency
+        edit form on error.
+    """
+    form = CurrencyForm(request.form)
+    form.obj_code = currency.code
+    if not form.validate():
+        for key in form.errors:
+            for error in form.errors[key]:
+                flash(error, "error")
+        session["form"] = urlencode(list(request.form.items()))
+        return redirect(inherit_next(url_for("accounting.currency.edit",
+                                             currency=currency)))
+    with db.session.no_autoflush:
+        form.populate_obj(currency)
+    if not currency.is_modified:
+        flash(lazy_gettext("The currency was not modified."), "success")
+        return redirect(inherit_next(url_for("accounting.currency.detail",
+                                             currency=currency)))
+    form.post_update(currency)
+    db.session.commit()
+    flash(lazy_gettext("The currency is updated successfully."), "success")
+    return redirect(inherit_next(url_for("accounting.currency.detail",
+                                         currency=currency)))
+
+
+@bp.post("/<currency:currency>/delete", endpoint="delete")
+@has_permission(can_edit)
+def delete_currency(currency: Currency) -> redirect:
+    """Deletes a currency.
+
+    :param currency: The currency.
+    :return: The redirection to the currency list on success, or the currency
+        detail on error.
+    """
+    currency.delete()
+    db.session.commit()
+    flash(lazy_gettext("The currency is deleted successfully."), "success")
+    return redirect(or_next(url_for("accounting.currency.list")))
+
+
+@api_bp.get("/exists-code", endpoint="exists")
+@has_permission(can_edit)
+def exists_code() -> dict[str, bool]:
+    """Validates whether a currency code exists.
+
+    :return: Whether the currency code exists.
+    """
+    return {"exists": db.session.get(Currency, request.args["q"]) is not None}
diff --git a/src/accounting/models.py b/src/accounting/models.py
index 0362b5c..e3d846a 100644
--- a/src/accounting/models.py
+++ b/src/accounting/models.py
@@ -313,3 +313,117 @@ class AccountL10n(db.Model):
     locale = db.Column(db.String, nullable=False, primary_key=True)
     title = db.Column(db.String, nullable=False)
     db.UniqueConstraint(account_id, locale)
+
+
+class Currency(db.Model):
+    """A currency."""
+    __tablename__ = "accounting_currencies"
+    """The table name."""
+    code = db.Column(db.String, nullable=False, primary_key=True)
+    """The code."""
+    name_l10n = db.Column("name", db.String, nullable=False)
+    """The name."""
+    created_at = db.Column(db.DateTime(timezone=True), nullable=False,
+                           server_default=db.func.now())
+    """The time of creation."""
+    created_by_id = db.Column(db.Integer,
+                              db.ForeignKey(user_pk_column,
+                                            onupdate="CASCADE"),
+                              nullable=False)
+    """The ID of the creator."""
+    created_by = db.relationship(user_cls, foreign_keys=created_by_id)
+    """The creator."""
+    updated_at = db.Column(db.DateTime(timezone=True), nullable=False,
+                           server_default=db.func.now())
+    """The time of last update."""
+    updated_by_id = db.Column(db.Integer,
+                              db.ForeignKey(user_pk_column,
+                                            onupdate="CASCADE"),
+                              nullable=False)
+    """The ID of the updator."""
+    updated_by = db.relationship(user_cls, foreign_keys=updated_by_id)
+    """The updator."""
+    l10n = db.relationship("CurrencyL10n", back_populates="currency",
+                           lazy=False)
+    """The localized names."""
+
+    def __str__(self) -> str:
+        """Returns the string representation of the currency.
+
+        :return: The string representation of the currency.
+        """
+        return F"{self.name} ({self.code})"
+
+    @property
+    def name(self) -> str:
+        """Returns the name in the current locale.
+
+        :return: The name in the current locale.
+        """
+        current_locale = str(get_locale())
+        if current_locale == current_app.config["BABEL_DEFAULT_LOCALE"]:
+            return self.name_l10n
+        for l10n in self.l10n:
+            if l10n.locale == current_locale:
+                return l10n.name
+        return self.name_l10n
+
+    @name.setter
+    def name(self, value: str) -> None:
+        """Sets the name in the current locale.
+
+        :param value: The new name.
+        :return: None.
+        """
+        if self.name_l10n is None:
+            self.name_l10n = value
+            return
+        current_locale = str(get_locale())
+        if current_locale == current_app.config["BABEL_DEFAULT_LOCALE"]:
+            self.name_l10n = value
+            return
+        for l10n in self.l10n:
+            if l10n.locale == current_locale:
+                l10n.name = value
+                return
+        self.l10n.append(CurrencyL10n(locale=current_locale, name=value))
+
+    @property
+    def is_modified(self) -> bool:
+        """Returns whether a product account was modified.
+
+        :return: True if modified, or False otherwise.
+        """
+        if db.session.is_modified(self):
+            return True
+        for l10n in self.l10n:
+            if db.session.is_modified(l10n):
+                return True
+        return False
+
+    def delete(self) -> None:
+        """Deletes the currency.
+
+        :return: None.
+        """
+        CurrencyL10n.query.filter(CurrencyL10n.currency == self).delete()
+        cls: t.Type[t.Self] = self.__class__
+        cls.query.filter(cls.code == self.code).delete()
+
+
+class CurrencyL10n(db.Model):
+    """A localized currency name."""
+    __tablename__ = "accounting_currencies_l10n"
+    """The table name."""
+    currency_code = db.Column(db.String,
+                              db.ForeignKey(Currency.code, onupdate="CASCADE",
+                                            ondelete="CASCADE"),
+                              nullable=False, primary_key=True)
+    """The currency code."""
+    currency = db.relationship(Currency, back_populates="l10n")
+    """The currency."""
+    locale = db.Column(db.String, nullable=False, primary_key=True)
+    """The locale."""
+    name = db.Column(db.String, nullable=False)
+    """The localized name."""
+    db.UniqueConstraint(currency_code, locale)
diff --git a/src/accounting/static/css/style.css b/src/accounting/static/css/style.css
index 72154ee..6bc8a18 100644
--- a/src/accounting/static/css/style.css
+++ b/src/accounting/static/css/style.css
@@ -56,6 +56,23 @@
     overflow-y: scroll;
 }
 
+/** The currency management. */
+.currency {
+    padding: 2em 1.5em;
+    margin: 1em;
+    background-color: #E9ECEF;
+    border-radius: 0.3em;
+    box-shadow: 0 4px 8px 0 rgba(0, 0, 0, 0.2), 0 6px 20px 0 rgba(0, 0, 0, 0.19);
+}
+.currency .currency-name {
+    font-size: 1.8rem;
+    font-weight: bolder;
+}
+.currency .currency-code {
+    font-size: 1.4rem;
+    color: #373b3e;
+}
+
 /* The Material Design text field (floating form control in Bootstrap) */
 .material-text-field {
     position: relative;
diff --git a/src/accounting/static/js/currency-form.js b/src/accounting/static/js/currency-form.js
new file mode 100644
index 0000000..9864a8f
--- /dev/null
+++ b/src/accounting/static/js/currency-form.js
@@ -0,0 +1,174 @@
+/* The Mia! Accounting Flask Project
+ * currency-form.js: The JavaScript for the currency form
+ */
+
+/*  Copyright (c) 2023 imacat.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+
+/* Author: imacat@mail.imacat.idv.tw (imacat)
+ * First written: 2023/2/6
+ */
+
+// Initializes the page JavaScript.
+document.addEventListener("DOMContentLoaded", function () {
+    document.getElementById("currency-code")
+        .onchange = validateCode;
+    document.getElementById("currency-name")
+        .onchange = validateName;
+    document.getElementById("currency-form")
+        .onsubmit = validateForm;
+});
+
+/**
+ * The asynchronous validation result
+ * @type {object}
+ * @private
+ */
+let isAsyncValid = {};
+
+/**
+ * Validates the form.
+ *
+ * @returns {boolean} true if valid, or false otherwise
+ * @private
+ */
+function validateForm() {
+    isAsyncValid = {
+        "code": false,
+        "_sync": false,
+    };
+    let isValid = true;
+    isValid = validateCode() && isValid;
+    isValid = validateName() && isValid;
+    isAsyncValid["_sync"] = isValid;
+    submitFormIfAllAsyncValid();
+    return false;
+}
+
+/**
+ * Submits the form if the whole form passed the asynchronous
+ * validations.
+ *
+ * @private
+ */
+function submitFormIfAllAsyncValid() {
+    let isValid = true;
+    Object.keys(isAsyncValid).forEach(function (key) {
+        isValid = isAsyncValid[key] && isValid;
+    });
+    if (isValid) {
+        document.getElementById("currency-form").submit()
+    }
+}
+
+/**
+ * Validates the code.
+ *
+ * @param changeEvent {Event} the change event, if invoked from onchange
+ * @returns {boolean} true if valid, or false otherwise
+ * @private
+ */
+function validateCode(changeEvent = null) {
+    const key = "code";
+    const isSubmission = changeEvent === null;
+    let hasAsyncValidation = false;
+    const field = document.getElementById("currency-code");
+    const error = document.getElementById("currency-code-error");
+    field.value = field.value.trim();
+    if (field.value === "") {
+        field.classList.add("is-invalid");
+        error.innerText = A_("Please fill in the code.");
+        return false;
+    }
+    const blocklist = JSON.parse(field.dataset.blocklist);
+    if (blocklist.includes(field.value)) {
+        field.classList.add("is-invalid");
+        error.innerText = A_("This code is not available.");
+        return false;
+    }
+    if (!field.value.match(/^[A-Z]{3}$/)) {
+        field.classList.add("is-invalid");
+        error.innerText = A_("Code can only be composed of 3 upper-cased letters.");
+        return false;
+    }
+    const original = field.dataset.original;
+    if (original === "" || field.value !== original) {
+        hasAsyncValidation = true;
+        validateAsyncCodeIsDuplicated(isSubmission, key);
+    }
+    if (!hasAsyncValidation) {
+        isAsyncValid[key] = true;
+        field.classList.remove("is-invalid");
+        error.innerText = "";
+    }
+    return true;
+}
+
+/**
+ * Validates asynchronously whether the code is duplicated.
+ * The boolean validation result is stored in isAsyncValid[key].
+ *
+ * @param isSubmission {boolean} whether this is invoked from a form submission
+ * @param key {string} the key to store the result in isAsyncValid
+ * @private
+ */
+function validateAsyncCodeIsDuplicated(isSubmission, key) {
+    const field = document.getElementById("currency-code");
+    const error = document.getElementById("currency-code-error");
+    const url = field.dataset.existsUrl;
+    const onLoad = function () {
+        if (this.status === 200) {
+            const result = JSON.parse(this.responseText);
+            if (result["exists"]) {
+                field.classList.add("is-invalid");
+                error.innerText = _("Code conflicts with another currency.");
+                if (isSubmission) {
+                    isAsyncValid[key] = false;
+                }
+                return;
+            }
+            field.classList.remove("is-invalid");
+            error.innerText = "";
+            if (isSubmission) {
+                isAsyncValid[key] = true;
+                submitFormIfAllAsyncValid();
+            }
+        }
+    };
+    const request = new XMLHttpRequest();
+    request.onload = onLoad;
+    request.open("GET", url + "?q=" + encodeURIComponent(field.value));
+    request.send();
+}
+
+/**
+ * Validates the name.
+ *
+ * @returns {boolean} true if valid, or false otherwise
+ * @private
+ */
+function validateName() {
+    const field = document.getElementById("currency-name");
+    const error = document.getElementById("currency-name-error");
+    field.value = field.value.trim();
+    if (field.value === "") {
+        field.classList.add("is-invalid");
+        error.innerText = A_("Please fill in the name.");
+        return false;
+    }
+    field.classList.remove("is-invalid");
+    error.innerText = "";
+    return true;
+}
diff --git a/src/accounting/templates/accounting/currency/create.html b/src/accounting/templates/accounting/currency/create.html
new file mode 100644
index 0000000..7664bff
--- /dev/null
+++ b/src/accounting/templates/accounting/currency/create.html
@@ -0,0 +1,28 @@
+{#
+The Mia! Accounting Flask Project
+create.html: The currency creation form
+
+ Copyright (c) 2023 imacat.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+Author: imacat@mail.imacat.idv.tw (imacat)
+First written: 2023/2/6
+#}
+{% extends "accounting/currency/include/form.html" %}
+
+{% block header %}{% block title %}{{ A_("Add a New Currency") }}{% endblock %}{% endblock %}
+
+{% block back_url %}{{ request.args.get("next") or url_for("accounting.currency.list") }}{% endblock %}
+
+{% block action_url %}{{ url_for("accounting.currency.store") }}{% endblock %}
diff --git a/src/accounting/templates/accounting/currency/detail.html b/src/accounting/templates/accounting/currency/detail.html
new file mode 100644
index 0000000..25dbbde
--- /dev/null
+++ b/src/accounting/templates/accounting/currency/detail.html
@@ -0,0 +1,90 @@
+{#
+The Mia! Accounting Flask Project
+detail.html: The currency detail
+
+ Copyright (c) 2023 imacat.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+Author: imacat@mail.imacat.idv.tw (imacat)
+First written: 2023/2/6
+#}
+{% extends "accounting/base.html" %}
+
+{% block header %}{% block title %}{{ obj }}{% endblock %}{% endblock %}
+
+{% block content %}
+
+<div class="btn-group mb-3">
+  <a class="btn btn-primary" href="{{ url_for("accounting.currency.list")|or_next }}">
+    <i class="fa-solid fa-circle-chevron-left"></i>
+    {{ A_("Back") }}
+  </a>
+  {% if can_edit_accounting() %}
+    <a class="btn btn-primary d-none d-md-inline" href="{{ url_for("accounting.currency.edit", currency=obj)|inherit_next }}">
+      <i class="fa-solid fa-gear"></i>
+      {{ A_("Settings") }}
+    </a>
+  {% endif %}
+  {% if can_edit_accounting() %}
+    <button class="btn btn-danger" type="button" data-bs-toggle="modal" data-bs-target="#delete-modal">
+      <i class="fa-solid fa-trash"></i>
+      {{ A_("Delete") }}
+    </button>
+  {% endif %}
+</div>
+
+{% if can_edit_accounting() %}
+  <div class="d-md-none material-fab">
+    <a class="btn btn-primary" href="{{ url_for("accounting.currency.edit", currency=obj)|inherit_next }}">
+      <i class="fa-solid fa-pen-to-square"></i>
+    </a>
+  </div>
+{% endif %}
+
+{% if can_edit_accounting() %}
+  <form id="delete-form" action="{{ url_for("accounting.currency.delete", currency=obj) }}" method="post">
+    <input id="csrf_token" type="hidden" name="csrf_token" value="{{ csrf_token() }}">
+    {% if "next" in request.args %}
+      <input type="hidden" name="next" value="{{ request.args["next"] }}">
+    {% endif %}
+    <div class="modal fade" id="delete-modal" tabindex="-1" aria-labelledby="delete-model-label" aria-hidden="true">
+      <div class="modal-dialog">
+        <div class="modal-content">
+          <div class="modal-header">
+            <h1 class="modal-title fs-5" id="delete-model-label">{{ A_("Delete Currency Confirmation") }}</h1>
+            <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close"></button>
+          </div>
+          <div class="modal-body">
+            {{ A_("Do you really want to delete this currency?") }}
+          </div>
+          <div class="modal-footer">
+            <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">{{ A_("Cancel") }}</button>
+            <button type="submit" class="btn btn-danger">{{ A_("Confirm") }}</button>
+          </div>
+        </div>
+      </div>
+    </div>
+  </form>
+{% endif %}
+
+<div class="currency col-sm-6">
+  <div class="currency-name">{{ obj.name }}</div>
+  <div class="currency-code">{{ obj.code }}</div>
+  <div class="small text-secondary fst-italic">
+    <div>{{ A_("Created") }} {{ obj.created_at }} {{ obj.created_by }}</div>
+    <div>{{ A_("Updated") }} {{ obj.updated_at }} {{ obj.updated_by }}</div>
+  </div>
+</div>
+
+{% endblock %}
diff --git a/src/accounting/templates/accounting/currency/edit.html b/src/accounting/templates/accounting/currency/edit.html
new file mode 100644
index 0000000..05a231a
--- /dev/null
+++ b/src/accounting/templates/accounting/currency/edit.html
@@ -0,0 +1,30 @@
+{#
+The Mia! Accounting Flask Project
+edit.html: The currency edit form
+
+ Copyright (c) 2023 imacat.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+Author: imacat@mail.imacat.idv.tw (imacat)
+First written: 2023/2/6
+#}
+{% extends "accounting/currency/include/form.html" %}
+
+{% block header %}{% block title %}{{ A_("%(currency)s Settings", currency=currency) }}{% endblock %}{% endblock %}
+
+{% block back_url %}{{ url_for("accounting.currency.detail", currency=currency)|inherit_next }}{% endblock %}
+
+{% block action_url %}{{ url_for("accounting.currency.update", currency=currency) }}{% endblock %}
+
+{% block original_code %}{{ currency.code }}{% endblock %}
diff --git a/src/accounting/templates/accounting/currency/include/form.html b/src/accounting/templates/accounting/currency/include/form.html
new file mode 100644
index 0000000..81f1b46
--- /dev/null
+++ b/src/accounting/templates/accounting/currency/include/form.html
@@ -0,0 +1,68 @@
+{#
+The Mia! Accounting Flask Project
+form.html: The currency form
+
+ Copyright (c) 2023 imacat.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+Author: imacat@mail.imacat.idv.tw (imacat)
+First written: 2023/2/6
+#}
+{% extends "accounting/base.html" %}
+
+{% block accounting_scripts %}
+  <script src="{{ url_for("accounting.static", filename="js/currency-form.js") }}"></script>
+{% endblock %}
+
+{% block content %}
+
+<div class="btn-group btn-actions mb-3">
+  <a class="btn btn-primary" role="button" href="{% block back_url %}{% endblock %}">
+    <i class="fa-solid fa-circle-chevron-left"></i>
+    {{ A_("Back") }}
+  </a>
+</div>
+
+<form id="currency-form" action="{% block action_url %}{% endblock %}" method="post">
+  {{ form.csrf_token }}
+  {% if "next" in request.args %}
+    <input type="hidden" name="next" value="{{ request.args["next"] }}">
+  {% endif %}
+  <div class="form-floating mb-3">
+    <input id="currency-code" class="form-control {% if form.code.errors %} is-invalid {% endif %}" type="text" name="code" value="{{ "" if form.code.data is none else form.code.data }}" placeholder=" " required="required" data-exists-url="{{ url_for("accounting.currency-api.exists") }}" data-original="{% block original_code %}{% endblock %}" data-blocklist="{{ form.CODE_BLOCKLIST|tojson|forceescape }}">
+    <label class="form-label" for="currency-code">{{ A_("Code") }}</label>
+    <div id="currency-code-error" class="invalid-feedback">{% if form.code.errors %}{{ form.code.errors[0] }}{% endif %}</div>
+  </div>
+
+  <div class="form-floating mb-3">
+    <input id="currency-name" class="form-control {% if form.name.errors %} is-invalid {% endif %}" type="text" name="name" value="{{ "" if form.name.data is none else form.name.data }}" placeholder=" " required="required">
+    <label class="form-label" for="currency-name">{{ A_("Name") }}</label>
+    <div id="currency-name-error" class="invalid-feedback">{% if form.name.errors %}{{ form.name.errors[0] }}{% endif %}</div>
+  </div>
+
+  <div class="d-none d-md-block">
+    <button class="btn btn-primary" type="submit">
+      <i class="fa-solid fa-floppy-disk"></i>
+      {{ A_("Save") }}
+    </button>
+  </div>
+
+  <div class="d-md-none material-fab">
+    <button class="btn btn-primary" type="submit">
+      <i class="fa-solid fa-floppy-disk"></i>
+    </button>
+  </div>
+</form>
+
+{% endblock %}
diff --git a/src/accounting/templates/accounting/currency/list.html b/src/accounting/templates/accounting/currency/list.html
new file mode 100644
index 0000000..4bb3c53
--- /dev/null
+++ b/src/accounting/templates/accounting/currency/list.html
@@ -0,0 +1,60 @@
+{#
+The Mia! Accounting Flask Project
+list.html: The currency list
+
+ Copyright (c) 2023 imacat.
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+     http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+Author: imacat@mail.imacat.idv.tw (imacat)
+First written: 2023/2/6
+#}
+{% extends "accounting/base.html" %}
+
+{% block header %}{% block title %}{% if "q" in request.args %}{{ A_("Search Result for \"%(query)s\"", query=request.args["q"]) }}{% else %}{{ A_("Currency Management") }}{% endif %}{% endblock %}{% endblock %}
+
+{% block content %}
+
+<div class="btn-group mb-2">
+  {% if can_edit_accounting() %}
+    <a class="btn btn-primary text-nowrap d-none d-md-block" href="{{ url_for("accounting.currency.create")|append_next }}">
+      <i class="fa-solid fa-plus"></i>
+      {{ A_("New") }}
+    </a>
+  {% endif %}
+  <form class="btn btn-primary d-flex input-group" action="{{ url_for("accounting.currency.list") }}" method="get" role="search">
+    <input id="search-input" class="form-control form-control-sm search-input" type="search" name="q" value="{{ request.args["q"] if "q" in request.args else "" }}" placeholder=" " required="required" aria-label="Search">
+    <label for="search-input" class="search-label">
+      <button type="submit">
+        <i class="fa-solid fa-magnifying-glass"></i>
+        {{ A_("Search") }}
+      </button>
+    </label>
+  </form>
+</div>
+
+{% if list %}
+  {% include "accounting/include/pagination.html" %}
+
+  <div class="list-group">
+  {% for item in list %}
+    <a class="list-group-item list-group-item-action" href="{{ url_for("accounting.currency.detail", currency=item)|append_next }}">
+      {{ item }}
+    </a>
+  {% endfor %}
+  </div>
+{% else %}
+  <p>{{ A_("There is no data.") }}</p>
+{% endif %}
+
+{% endblock %}
diff --git a/src/accounting/templates/accounting/include/nav.html b/src/accounting/templates/accounting/include/nav.html
index e52175d..0a98d84 100644
--- a/src/accounting/templates/accounting/include/nav.html
+++ b/src/accounting/templates/accounting/include/nav.html
@@ -38,6 +38,12 @@ First written: 2023/1/26
           {{ A_("Base Accounts") }}
         </a>
       </li>
+      <li>
+        <a class="dropdown-item {% if request.endpoint.startswith("accounting.currency.") %} active {% endif %}" href="{{ url_for("accounting.currency.list") }}">
+          <i class="fa-solid fa-list"></i>
+          {{ A_("Currencies") }}
+        </a>
+      </li>
     </ul>
   </li>
 {% endif %}
diff --git a/tests/test_currency.py b/tests/test_currency.py
new file mode 100644
index 0000000..f0b5a7e
--- /dev/null
+++ b/tests/test_currency.py
@@ -0,0 +1,560 @@
+# The Mia! Accounting Flask Project.
+# Author: imacat@mail.imacat.idv.tw (imacat), 2023/2/1
+
+#  Copyright (c) 2023 imacat.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+"""The test for the currency management.
+
+"""
+import time
+import unittest
+
+import httpx
+from click.testing import Result
+from flask import Flask
+from flask.testing import FlaskCliRunner
+
+from test_site import create_app
+from testlib import get_client, set_locale
+
+
+class CurrencyCommandTestCase(unittest.TestCase):
+    """The account console command test case."""
+
+    def setUp(self) -> None:
+        """Sets up the test.
+        This is run once per test.
+
+        :return: None.
+        """
+        self.app: Flask = create_app(is_testing=True)
+
+        runner: FlaskCliRunner = self.app.test_cli_runner()
+        with self.app.app_context():
+            from accounting.database import db
+            from accounting.models import Currency, CurrencyL10n
+            result: Result
+            result = runner.invoke(args="init-db")
+            self.assertEqual(result.exit_code, 0)
+            CurrencyL10n.query.delete()
+            Currency.query.delete()
+            db.session.commit()
+
+    def test_init(self) -> None:
+        """Tests the "accounting-init-currencies" console command.
+
+        :return: None.
+        """
+        from accounting.models import Currency, CurrencyL10n
+        runner: FlaskCliRunner = self.app.test_cli_runner()
+        with self.app.app_context():
+            result: Result = runner.invoke(
+                args=["accounting-init-currencies", "-u", "editor"])
+            self.assertEqual(result.exit_code, 0)
+            currencies: list[Currency] = Currency.query.all()
+            l10n: list[CurrencyL10n] = CurrencyL10n.query.all()
+        self.assertEqual(len(currencies), 2)
+        self.assertEqual(len(l10n), 2 * 2)
+        l10n_keys: set[str] = {f"{x.currency_code}-{x.locale}" for x in l10n}
+        for currency in currencies:
+            self.assertIn(f"{currency.code}-zh_Hant", l10n_keys)
+            self.assertIn(f"{currency.code}-zh_Hant", l10n_keys)
+
+
+class CurrencyTestCase(unittest.TestCase):
+    """The currency test case."""
+
+    def setUp(self) -> None:
+        """Sets up the test.
+        This is run once per test.
+
+        :return: None.
+        """
+        self.app: Flask = create_app(is_testing=True)
+
+        runner: FlaskCliRunner = self.app.test_cli_runner()
+        with self.app.app_context():
+            from accounting.database import db
+            from accounting.models import Currency, CurrencyL10n
+            result: Result
+            result = runner.invoke(args="init-db")
+            self.assertEqual(result.exit_code, 0)
+            CurrencyL10n.query.delete()
+            Currency.query.delete()
+            db.session.commit()
+
+        self.client, self.csrf_token = get_client(self, self.app, "editor")
+        response: httpx.Response
+
+        response = self.client.post("/accounting/currencies/store",
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": "ZZA",
+                                          "name": "Testing Dollar #A"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         "/accounting/currencies/ZZA")
+
+        response = self.client.post("/accounting/currencies/store",
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": "ZZB",
+                                          "name": "Testing Dollar #B"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         "/accounting/currencies/ZZB")
+
+    def test_nobody(self) -> None:
+        """Test the permission as nobody.
+
+        :return: None.
+        """
+        client, csrf_token = get_client(self, self.app, "nobody")
+        response: httpx.Response
+
+        response = client.get("/accounting/currencies")
+        self.assertEqual(response.status_code, 403)
+
+        response = client.get("/accounting/currencies/ZZA")
+        self.assertEqual(response.status_code, 403)
+
+        response = client.get("/accounting/currencies/create")
+        self.assertEqual(response.status_code, 403)
+
+        response = client.post("/accounting/currencies/store",
+                               data={"csrf_token": csrf_token,
+                                     "code": "ZZC",
+                                     "name": "Testing Dollar #C"})
+        self.assertEqual(response.status_code, 403)
+
+        response = client.get("/accounting/currencies/ZZA/edit")
+        self.assertEqual(response.status_code, 403)
+
+        response = client.post("/accounting/currencies/ZZA/update",
+                               data={"csrf_token": csrf_token,
+                                     "code": "ZZD",
+                                     "name": "Testing Dollar #D"})
+        self.assertEqual(response.status_code, 403)
+
+        response = client.post("/accounting/currencies/ZZB/delete",
+                               data={"csrf_token": csrf_token})
+        self.assertEqual(response.status_code, 403)
+
+    def test_viewer(self) -> None:
+        """Test the permission as viewer.
+
+        :return: None.
+        """
+        client, csrf_token = get_client(self, self.app, "viewer")
+        response: httpx.Response
+
+        response = client.get("/accounting/currencies")
+        self.assertEqual(response.status_code, 200)
+
+        response = client.get("/accounting/currencies/ZZA")
+        self.assertEqual(response.status_code, 200)
+
+        response = client.get("/accounting/currencies/create")
+        self.assertEqual(response.status_code, 403)
+
+        response = client.post("/accounting/currencies/store",
+                               data={"csrf_token": csrf_token,
+                                     "code": "ZZC",
+                                     "name": "Testing Dollar #C"})
+        self.assertEqual(response.status_code, 403)
+
+        response = client.get("/accounting/currencies/ZZA/edit")
+        self.assertEqual(response.status_code, 403)
+
+        response = client.post("/accounting/currencies/ZZA/update",
+                               data={"csrf_token": csrf_token,
+                                     "code": "ZZD",
+                                     "name": "Testing Dollar #D"})
+        self.assertEqual(response.status_code, 403)
+
+        response = client.post("/accounting/currencies/ZZB/delete",
+                               data={"csrf_token": csrf_token})
+        self.assertEqual(response.status_code, 403)
+
+    def test_editor(self) -> None:
+        """Test the permission as editor.
+
+        :return: None.
+        """
+        response: httpx.Response
+
+        response = self.client.get("/accounting/currencies")
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.get("/accounting/currencies/ZZA")
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.get("/accounting/currencies/create")
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.post("/accounting/currencies/store",
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": "ZZC",
+                                          "name": "Testing Dollar #C"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         "/accounting/currencies/ZZC")
+
+        response = self.client.get("/accounting/currencies/ZZA/edit")
+        self.assertEqual(response.status_code, 200)
+
+        response = self.client.post("/accounting/currencies/ZZA/update",
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": "ZZD",
+                                          "name": "Testing Dollar #D"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         "/accounting/currencies/ZZD")
+
+        response = self.client.post("/accounting/currencies/ZZB/delete",
+                                    data={"csrf_token": self.csrf_token})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         "/accounting/currencies")
+
+    def test_add(self) -> None:
+        """Tests to add the currencies.
+
+        :return: None.
+        """
+        from accounting.models import Currency
+        from test_site import db
+        zzc_code, zzc_name = "ZZC", "Testing Dollar #C"
+        create_uri: str = "/accounting/currencies/create"
+        store_uri: str = "/accounting/currencies/store"
+        response: httpx.Response
+
+        with self.app.app_context():
+            self.assertEqual({x.code for x in Currency.query.all()},
+                             {"ZZA", "ZZB"})
+
+        # Missing CSRF token
+        response = self.client.post(store_uri,
+                                    data={"code": zzc_code,
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 400)
+
+        # CSRF token mismatch
+        response = self.client.post(store_uri,
+                                    data={"csrf_token": f"{self.csrf_token}-2",
+                                          "code": zzc_code,
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 400)
+
+        # Empty code
+        response = self.client.post(store_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": " ",
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], create_uri)
+
+        # Blocked code, with spaces to be stripped
+        response = self.client.post(store_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": " create ",
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], create_uri)
+
+        # Bad code
+        response = self.client.post(store_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": " zzc ",
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], create_uri)
+
+        # Empty name
+        response = self.client.post(store_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": zzc_code,
+                                          "name": " "})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], create_uri)
+
+        # Success, with spaces to be stripped
+        response = self.client.post(store_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": f" {zzc_code} ",
+                                          "name": f" {zzc_name} "})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         f"/accounting/currencies/{zzc_code}")
+
+        # Duplicated code
+        response = self.client.post(store_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": zzc_code,
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], create_uri)
+
+        with self.app.app_context():
+            self.assertEqual({x.code for x in Currency.query.all()},
+                             {"ZZA", "ZZB", zzc_code})
+
+            zzc: Currency = db.session.get(Currency, zzc_code)
+            self.assertEqual(zzc.code, zzc_code)
+            self.assertEqual(zzc.name_l10n, zzc_name)
+
+    def test_basic_update(self) -> None:
+        """Tests the basic rules to update a user.
+
+        :return: None.
+        """
+        from accounting.models import Currency
+        from test_site import db
+        zza_code: str = "ZZA"
+        zzc_code, zzc_name = "ZZC", "Testing Dollar #C"
+        edit_uri: str = f"/accounting/currencies/{zza_code}/edit"
+        update_uri: str = f"/accounting/currencies/{zza_code}/update"
+        response: httpx.Response
+
+        # Success, with spaces to be stripped
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": f" {zza_code} ",
+                                          "name": f" {zzc_name} "})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         f"/accounting/currencies/{zza_code}")
+
+        with self.app.app_context():
+            zza: Currency = db.session.get(Currency, zza_code)
+            self.assertEqual(zza.code, zza_code)
+            self.assertEqual(zza.name_l10n, zzc_name)
+
+        # Empty code
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": " ",
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], edit_uri)
+
+        # Blocked code, with spaces to be stripped
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": " create ",
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], edit_uri)
+
+        # Bad code
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": "abc/def",
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], edit_uri)
+
+        # Empty name
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": zzc_code,
+                                          "name": " "})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], edit_uri)
+
+        # Duplicated code
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": "ZZB",
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], edit_uri)
+
+        # Change code
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": zzc_code,
+                                          "name": zzc_name})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         f"/accounting/currencies/{zzc_code}")
+
+        response = self.client.get(f"/accounting/currencies/{zza_code}")
+        self.assertEqual(response.status_code, 404)
+
+        response = self.client.get(f"/accounting/currencies/{zzc_code}")
+        self.assertEqual(response.status_code, 200)
+
+    def test_update_not_modified(self) -> None:
+        """Tests that the data is not modified.
+
+        :return: None.
+        """
+        from accounting.models import Currency
+        from test_site import db
+        zza_code, zza_name = "ZZA", "Testing Dollar #A"
+        detail_uri: str = f"/accounting/currencies/{zza_code}"
+        update_uri: str = f"/accounting/currencies/{zza_code}/update"
+        response: httpx.Response
+        time.sleep(1)
+
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": f" {zza_code} ",
+                                          "name": f" {zza_name} "})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], detail_uri)
+
+        with self.app.app_context():
+            zza: Currency = db.session.get(Currency, zza_code)
+            self.assertIsNotNone(zza)
+            self.assertEqual(zza.created_at, zza.updated_at)
+
+        response = self.client.post(update_uri,
+                                    data={"csrf_token": self.csrf_token,
+                                          "code": zza_code,
+                                          "name": "Testing Dollar #C"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"], detail_uri)
+
+        with self.app.app_context():
+            zza: Currency = db.session.get(Currency, zza_code)
+            self.assertIsNotNone(zza)
+            self.assertNotEqual(zza.created_at, zza.updated_at)
+
+    def test_created_updated_by(self) -> None:
+        """Tests the created-by and updated-by record.
+
+        :return: None.
+        """
+        from accounting.models import Currency
+        from test_site import db
+        zza_code, zza_name = "ZZA", "Testing Dollar #A"
+        editor_username, editor2_username = "editor", "editor2"
+        client, csrf_token = get_client(self, self.app, editor2_username)
+        response: httpx.Response
+
+        with self.app.app_context():
+            currency: Currency = db.session.get(Currency, zza_code)
+            self.assertEqual(currency.created_by.username, editor_username)
+            self.assertEqual(currency.updated_by.username, editor_username)
+
+        response = client.post(f"/accounting/currencies/{zza_code}/update",
+                               data={"csrf_token": csrf_token,
+                                     "code": zza_code,
+                                     "name": f"{zza_name}-2"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         f"/accounting/currencies/{zza_code}")
+
+        with self.app.app_context():
+            currency: Currency = db.session.get(Currency, zza_code)
+            self.assertEqual(currency.created_by.username, editor_username)
+            self.assertEqual(currency.updated_by.username, editor2_username)
+
+    def test_l10n(self) -> None:
+        """Tests the localization.
+
+        :return: None
+        """
+        from accounting.models import Currency
+        from test_site import db
+        zza_code, zza_name = "ZZA", "Testing Dollar #A"
+
+        with self.app.app_context():
+            zza: Currency = db.session.get(Currency, zza_code)
+            self.assertEqual(zza.name_l10n, zza_name)
+            self.assertEqual(zza.l10n, [])
+
+        set_locale(self, self.client, self.csrf_token, "zh_Hant")
+
+        response = self.client.post(
+            f"/accounting/currencies/{zza_code}/update",
+            data={"csrf_token": self.csrf_token,
+                  "code": zza_code,
+                  "name": f"{zza_name}-zh_Hant"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         f"/accounting/currencies/{zza_code}")
+
+        with self.app.app_context():
+            zza: Currency = db.session.get(Currency, zza_code)
+            self.assertEqual(zza.name_l10n, zza_name)
+            self.assertEqual({(x.locale, x.name) for x in zza.l10n},
+                             {("zh_Hant", f"{zza_name}-zh_Hant")})
+
+        set_locale(self, self.client, self.csrf_token, "en")
+
+        response = self.client.post(
+            f"/accounting/currencies/{zza_code}/update",
+            data={"csrf_token": self.csrf_token,
+                  "code": zza_code,
+                  "name": f"{zza_name}-2"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         f"/accounting/currencies/{zza_code}")
+
+        with self.app.app_context():
+            zza: Currency = db.session.get(Currency, zza_code)
+            self.assertEqual(zza.name_l10n, f"{zza_name}-2")
+            self.assertEqual({(x.locale, x.name) for x in zza.l10n},
+                             {("zh_Hant", f"{zza_name}-zh_Hant")})
+
+        set_locale(self, self.client, self.csrf_token, "zh_Hant")
+
+        response = self.client.post(
+            f"/accounting/currencies/{zza_code}/update",
+            data={"csrf_token": self.csrf_token,
+                  "code": zza_code,
+                  "name": f"{zza_name}-zh_Hant-2"})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         f"/accounting/currencies/{zza_code}")
+
+        with self.app.app_context():
+            zza: Currency = db.session.get(Currency, zza_code)
+            self.assertEqual(zza.name_l10n, f"{zza_name}-2")
+            self.assertEqual({(x.locale, x.name) for x in zza.l10n},
+                             {("zh_Hant", f"{zza_name}-zh_Hant-2")})
+
+    def test_delete(self) -> None:
+        """Tests to delete a currency.
+
+        :return: None.
+        """
+        from accounting.models import Currency
+        zza_code, zzb_code = "ZZA", "ZZB"
+        response: httpx.Response
+
+        with self.app.app_context():
+            self.assertEqual({x.code for x in Currency.query.all()},
+                             {zza_code, zzb_code})
+
+        response = self.client.get(f"/accounting/currencies/{zza_code}")
+        self.assertEqual(response.status_code, 200)
+        response = self.client.post(
+            f"/accounting/currencies/{zza_code}/delete",
+            data={"csrf_token": self.csrf_token})
+        self.assertEqual(response.status_code, 302)
+        self.assertEqual(response.headers["Location"],
+                         "/accounting/currencies")
+
+        with self.app.app_context():
+            self.assertEqual({x.code for x in Currency.query.all()},
+                             {zzb_code})
+
+        response = self.client.get(f"/accounting/currencies/{zza_code}")
+        self.assertEqual(response.status_code, 404)
+        response = self.client.post(
+            f"/accounting/currencies/{zza_code}/delete",
+            data={"csrf_token": self.csrf_token})
+        self.assertEqual(response.status_code, 404)
diff --git a/tests/testlib.py b/tests/testlib.py
index 95f5ff9..8b812f1 100644
--- a/tests/testlib.py
+++ b/tests/testlib.py
@@ -17,6 +17,7 @@
 """The common test libraries.
 
 """
+import typing as t
 from html.parser import HTMLParser
 from unittest import TestCase
 
@@ -75,3 +76,21 @@ def get_csrf_token(test_case: TestCase, client: httpx.Client, uri: str) -> str:
     parser.feed(response.text)
     test_case.assertIsNotNone(parser.csrf_token)
     return parser.csrf_token
+
+
+def set_locale(test_case: TestCase, client: httpx.Client, csrf_token: str,
+               locale: t.Literal["en", "zh_Hant", "zh_Hans"]) -> None:
+    """Sets the current locale.
+
+    :param test_case: The test case.
+    :param client: The test client.
+    :param csrf_token: The CSRF token.
+    :param locale: The locale.
+    :return: None.
+    """
+    response: httpx.Response = client.post("/locale",
+                                           data={"csrf_token": csrf_token,
+                                                 "locale": locale,
+                                                 "next": "/next"})
+    test_case.assertEqual(response.status_code, 302)
+    test_case.assertEqual(response.headers["Location"], "/next")