diff --git a/mia_core/utils.py b/mia_core/utils.py
new file mode 100644
index 0000000..a367249
--- /dev/null
+++ b/mia_core/utils.py
@@ -0,0 +1,106 @@
+import urllib.parse
+
+
+class UrlBuilder:
+    """The URL builder.
+
+    Attributes:
+        base_path (str): the base path
+        params (list[Param]): The query parameters
+    """
+    base_path = None
+    params = []
+
+    def __init__(self, start_url):
+        """Constructs a new URL builder.
+
+        Args:
+            start_url (str): The URL to start with
+        """
+        pos = start_url.find("?")
+        if pos == -1:
+            self.base_path = start_url
+            return
+        self.base_path = start_url[:pos]
+        self.params = []
+        for piece in start_url[pos+1:].split("&"):
+            pos = piece.find("=")
+            name = urllib.parse.unquote(piece[:pos])
+            value = urllib.parse.unquote(piece[pos+1:])
+            self.params.append(self.Param(name, value))
+
+    def add_param(self, name, value):
+        """Adds a query parameter.
+
+        Args:
+            name (str): The parameter name
+            value (str): The parameter value
+
+        Returns:
+            (UrlBuilder): The URL builder itself, with the parameter
+            modified.
+        """
+        self.params.append(self.Param(name, value))
+        return self
+
+    def del_param(self, name):
+        """Removes a query parameter.
+
+        Args:
+            name (str): The parameter name
+
+        Returns:
+            (UrlBuilder): The URL builder itself, with the parameter
+            modified.
+        """
+        self.params = [x for x in self.params if x.name != name]
+        return self
+
+    def set_param(self, name, value):
+        """Sets a query parameter.  The current parameters with the
+        same name will be replaced.
+
+        Args:
+            name (str): The parameter name
+            value (str): The parameter value
+
+        Returns:
+            (UrlBuilder): The URL builder itself, with the parameter
+            modified.
+        """
+        return self.del_param(name).add_param(name, value)
+
+    def __str__(self):
+        return self.base_path + "&".join([str(x) for x in self.params])
+
+    class Param:
+        """A query parameter.
+
+        Attributes:
+            name (str): The parameter name
+            value (str): The parameter value
+        """
+        name = None
+        value = None
+
+        def __init__(self, name, value):
+            """Constructs a new query parameter
+
+            Args:
+                name (str): The parameter name
+                value (str): The parameter value
+            """
+            self.name = name
+            self.value = value
+
+        def __str__(self):
+            """Returns the string representation of this query
+            parameter.
+
+            Returns:
+                (str) The string representation of this query
+                parameter
+            """
+            return "%s=%s" % (
+                urllib.parse.quote(self.name),
+                urllib.parse.quote(self.value))