diff --git a/src/py/flwr/common/config.py b/src/py/flwr/common/config.py
index 20de00a6fba9..e615e497b808 100644
--- a/src/py/flwr/common/config.py
+++ b/src/py/flwr/common/config.py
@@ -16,7 +16,7 @@
 
 import os
 from pathlib import Path
-from typing import Any, Dict, Optional, Union
+from typing import Any, Dict, List, Optional, Tuple, Union
 
 import tomli
 
@@ -30,7 +30,7 @@ def get_flwr_dir(provided_path: Optional[str] = None) -> Path:
         return Path(
             os.getenv(
                 FLWR_HOME,
-                f"{os.getenv('XDG_DATA_HOME', os.getenv('HOME'))}/.flwr",
+                Path(f"{os.getenv('XDG_DATA_HOME', os.getenv('HOME'))}") / ".flwr",
             )
         )
     return Path(provided_path).absolute()
@@ -71,3 +71,46 @@ def get_project_config(project_dir: Union[str, Path]) -> Dict[str, Any]:
         )
 
     return config
+
+
+def flatten_dict(raw_dict: Dict[str, Any], parent_key: str = "") -> Dict[str, str]:
+    """Flatten dict by joining nested keys with a given separator."""
+    items: List[Tuple[str, str]] = []
+    separator: str = "."
+    for k, v in raw_dict.items():
+        new_key = f"{parent_key}{separator}{k}" if parent_key else k
+        if isinstance(v, dict):
+            items.extend(flatten_dict(v, parent_key=new_key).items())
+        elif isinstance(v, str):
+            items.append((new_key, v))
+        else:
+            raise ValueError(
+                f"The value for key {k} needs to be a `str` or a `dict`.",
+            )
+    return dict(items)
+
+
+def parse_config_args(
+    config_overrides: Optional[str],
+    separator: str = ",",
+) -> Dict[str, str]:
+    """Parse separator separated list of key-value pairs separated by '='."""
+    overrides: Dict[str, str] = {}
+
+    if config_overrides is None:
+        return overrides
+
+    overrides_list = config_overrides.split(separator)
+    if (
+        len(overrides_list) == 1
+        and "=" not in overrides_list
+        and overrides_list[0].endswith(".toml")
+    ):
+        with Path(overrides_list[0]).open("rb") as config_file:
+            overrides = flatten_dict(tomli.load(config_file))
+    else:
+        for kv_pair in overrides_list:
+            key, value = kv_pair.split("=")
+            overrides[key] = value
+
+    return overrides
diff --git a/src/py/flwr/common/config_test.py b/src/py/flwr/common/config_test.py
new file mode 100644
index 000000000000..d30f0d5cc755
--- /dev/null
+++ b/src/py/flwr/common/config_test.py
@@ -0,0 +1,164 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# 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.
+# ==============================================================================
+"""Test util functions handling Flower config."""
+
+import os
+import textwrap
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+
+from .config import (
+    flatten_dict,
+    get_flwr_dir,
+    get_project_config,
+    get_project_dir,
+    parse_config_args,
+)
+
+# Mock constants
+FAB_CONFIG_FILE = "pyproject.toml"
+
+
+def test_get_flwr_dir_with_provided_path() -> None:
+    """Test get_flwr_dir with a provided valid path."""
+    provided_path = "."
+    assert get_flwr_dir(provided_path) == Path(provided_path).absolute()
+
+
+def test_get_flwr_dir_without_provided_path() -> None:
+    """Test get_flwr_dir without a provided path, using default home directory."""
+    with patch.dict(os.environ, {"HOME": "/home/user"}):
+        assert get_flwr_dir() == Path("/home/user/.flwr")
+
+
+def test_get_flwr_dir_with_flwr_home() -> None:
+    """Test get_flwr_dir with FLWR_HOME environment variable set."""
+    with patch.dict(os.environ, {"FLWR_HOME": "/custom/flwr/home"}):
+        assert get_flwr_dir() == Path("/custom/flwr/home")
+
+
+def test_get_flwr_dir_with_xdg_data_home() -> None:
+    """Test get_flwr_dir with FLWR_HOME environment variable set."""
+    with patch.dict(os.environ, {"XDG_DATA_HOME": "/custom/data/home"}):
+        assert get_flwr_dir() == Path("/custom/data/home/.flwr")
+
+
+def test_get_project_dir_invalid_fab_id() -> None:
+    """Test get_project_dir with an invalid fab_id."""
+    with pytest.raises(ValueError):
+        get_project_dir("invalid_fab_id", "1.0.0")
+
+
+def test_get_project_dir_valid() -> None:
+    """Test get_project_dir with an valid fab_id and version."""
+    app_path = get_project_dir("app_name/user", "1.0.0", flwr_dir=".")
+    assert app_path == Path("apps") / "app_name" / "user" / "1.0.0"
+
+
+def test_get_project_config_file_not_found() -> None:
+    """Test get_project_config when the configuration file is not found."""
+    with pytest.raises(FileNotFoundError):
+        get_project_config("/invalid/dir")
+
+
+def test_get_project_config_file_valid(tmp_path: Path) -> None:
+    """Test get_project_config when the configuration file is not found."""
+    pyproject_toml_content = """
+        [build-system]
+        requires = ["hatchling"]
+        build-backend = "hatchling.build"
+
+        [project]
+        name = "fedgpt"
+        version = "1.0.0"
+        description = ""
+        license = {text = "Apache License (2.0)"}
+        dependencies = [
+            "flwr[simulation]>=1.9.0,<2.0",
+            "numpy>=1.21.0",
+        ]
+
+        [flower]
+        publisher = "flwrlabs"
+
+        [flower.components]
+        serverapp = "fedgpt.server:app"
+        clientapp = "fedgpt.client:app"
+
+        [flower.config]
+        num_server_rounds = "10"
+        momentum = "0.1"
+        lr = "0.01"
+    """
+    expected_config = {
+        "build-system": {"build-backend": "hatchling.build", "requires": ["hatchling"]},
+        "project": {
+            "name": "fedgpt",
+            "version": "1.0.0",
+            "description": "",
+            "license": {"text": "Apache License (2.0)"},
+            "dependencies": ["flwr[simulation]>=1.9.0,<2.0", "numpy>=1.21.0"],
+        },
+        "flower": {
+            "publisher": "flwrlabs",
+            "components": {
+                "serverapp": "fedgpt.server:app",
+                "clientapp": "fedgpt.client:app",
+            },
+            "config": {
+                "num_server_rounds": "10",
+                "momentum": "0.1",
+                "lr": "0.01",
+            },
+        },
+    }
+    # Current directory
+    origin = Path.cwd()
+
+    try:
+        # Change into the temporary directory
+        os.chdir(tmp_path)
+        with open(FAB_CONFIG_FILE, "w", encoding="utf-8") as f:
+            f.write(textwrap.dedent(pyproject_toml_content))
+
+        # Execute
+        config = get_project_config(tmp_path)
+
+        # Assert
+        assert config == expected_config
+    finally:
+        os.chdir(origin)
+
+
+def test_flatten_dict() -> None:
+    """Test flatten_dict with a nested dictionary."""
+    raw_dict = {"a": {"b": {"c": "d"}}, "e": "f"}
+    expected = {"a.b.c": "d", "e": "f"}
+    assert flatten_dict(raw_dict) == expected
+
+
+def test_parse_config_args_none() -> None:
+    """Test parse_config_args with None as input."""
+    assert not parse_config_args(None)
+
+
+def test_parse_config_args_overrides() -> None:
+    """Test parse_config_args with key-value pairs."""
+    assert parse_config_args("key1=value1,key2=value2") == {
+        "key1": "value1",
+        "key2": "value2",
+    }