diff --git a/.github/workflows/type-checking.yml b/.github/workflows/type-checking.yml
new file mode 100644
index 00000000..c0684925
--- /dev/null
+++ b/.github/workflows/type-checking.yml
@@ -0,0 +1,30 @@
+name: Type Checking
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ '*' ]
+
+jobs:
+  mypy:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        fetch-depth: 0
+
+    - name: Set up Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: '3.12'
+        cache: 'pip'
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install ".[dev]"
+
+    - name: Run mypy
+      run: |
+        mypy powerplantmatching
diff --git a/.gitignore b/.gitignore
index bb9ff7d2..c7e995b3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -92,3 +92,7 @@ doc/_build
 doc/api
 .vscode
 test.ipynb
+
+# temporary
+.devcontainer/
+.repoai/
diff --git a/powerplantmatching/core.py b/powerplantmatching/core.py
index b1fed2a1..11f7c251 100644
--- a/powerplantmatching/core.py
+++ b/powerplantmatching/core.py
@@ -26,8 +26,8 @@
     "downloaders": {},
 }
 
-makedirs(join(package_config["data_dir"], "data", "in"), exist_ok=True)
-makedirs(join(package_config["data_dir"], "data", "out"), exist_ok=True)
+makedirs(join(str(package_config["data_dir"]), "data", "in"), exist_ok=True)
+makedirs(join(str(package_config["data_dir"]), "data", "out"), exist_ok=True)
 
 
 def _package_data(fn):
@@ -35,14 +35,14 @@ def _package_data(fn):
 
 
 def _data_in(fn):
-    return join(package_config["data_dir"], "data", "in", fn)
+    return join(str(package_config["data_dir"]), "data", "in", fn)
 
 
 def _data_out(fn, config):
     if config is None:
-        directory = join(package_config["data_dir"], "data", "out", "default")
+        directory = join(str(package_config["data_dir"]), "data", "out", "default")
     else:
-        directory = join(package_config["data_dir"], "data", "out", config["hash"])
+        directory = join(str(package_config["data_dir"]), "data", "out", config["hash"])
     makedirs(directory, exist_ok=True)
     return join(directory, fn)
 
@@ -60,7 +60,7 @@ def _data_out(fn, config):
 logFormatter = logging.Formatter(
     "%(asctime)s [%(threadName)-12.12s] [%(levelname)-5.5s]  %(message)s"
 )
-fileHandler = logging.FileHandler(join(package_config["data_dir"], "PPM.log"))
+fileHandler = logging.FileHandler(join(str(package_config["data_dir"]), "PPM.log"))
 fileHandler.setFormatter(logFormatter)
 logger.addHandler(fileHandler)
 # logger.info('Initialization complete.')
diff --git a/powerplantmatching/plot.py b/powerplantmatching/plot.py
index d1d77b7e..67b63121 100644
--- a/powerplantmatching/plot.py
+++ b/powerplantmatching/plot.py
@@ -23,7 +23,8 @@
 import numpy as np
 import pandas as pd
 import seaborn as sns
-from matplotlib import cycler, rcParams
+from cycler import cycler
+from matplotlib import rcParams
 from matplotlib.legend_handler import HandlerPatch
 from matplotlib.lines import Line2D
 
diff --git a/pyproject.toml b/pyproject.toml
index eac6c047..333c01e8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -58,7 +58,22 @@ docs= [
     "nbsphinx",
     "sphinx-automodapi",
 ]
-dev= ["pre-commit", "pytest", "pytest-cov"]
+dev= [
+    "pre-commit",
+    "pytest",
+    "pytest-cov",
+    "mypy",
+    "types-requests",
+    "types-PyYAML",
+    "pandas-stubs",
+    "types-tqdm",
+    "types-six"
+]
+
+# Add optional dependencies for plotting
+plotting= [
+    "cartopy"
+]
 
  # setuptools_scm settings
 
@@ -92,3 +107,33 @@ select = [
     'TID', # flake8-tidy-imports
     'NPY', # numpy
 ]
+
+# Add basic mypy configuration
+[tool.mypy]
+python_version = "3.9"
+warn_unused_configs = true
+disallow_untyped_defs = false
+disallow_incomplete_defs = false
+# Ignore class-level imports in accessor.py
+disable_error_code = ["misc"]
+
+# Ignore missing imports for external libraries
+[[tool.mypy.overrides]]
+module = [
+    "matplotlib.*",
+    "seaborn.*",
+    "networkx.*",
+    "pycountry.*",
+    "country_converter.*",
+    "geopy.*",
+    "unidecode.*",
+    "entsoe.*",
+    "yaml.*",
+    "scipy.*",
+    "pandas.*",
+    "tqdm.*",
+    "deprecation.*",
+    "cartopy.*",
+    "six.*",
+]
+ignore_missing_imports = true