diff --git a/config.py b/config.py
new file mode 100644
index 0000000..5d4d7ae
--- /dev/null
+++ b/config.py
@@ -0,0 +1,58 @@
+import os
+import tomllib
+
+CONFIG_PATH = os.path.expanduser("~/.config/tueit-transcriber/config.toml")
+
+DEFAULTS = {
+    "ollama": {
+        "base_url": "http://localhost:11434",
+        "model": "gemma3:12b",
+    },
+    "whisper": {
+        "model": "large-v3",
+        "language": "de",
+        "device": "auto",  # "auto" = use GPU if ROCm available, else CPU
+    },
+    "server": {
+        "port": 8765,
+    },
+    "output": {
+        "path": os.path.expanduser(
+            "~/cloud.shron.de/Hetzner Storagebox/work"
+        ),
+    },
+    "pid_file": os.path.expanduser("~/.local/run/tueit-transcriber.pid"),
+}
+
+
+def load() -> dict:
+    os.makedirs(os.path.dirname(CONFIG_PATH), exist_ok=True)
+    if not os.path.exists(CONFIG_PATH):
+        _write_defaults()
+    with open(CONFIG_PATH, "rb") as f:
+        on_disk = tomllib.load(f)
+    return _deep_merge(DEFAULTS, on_disk)
+
+
+def _deep_merge(base: dict, override: dict) -> dict:
+    result = dict(base)
+    for k, v in override.items():
+        if k in result and isinstance(result[k], dict) and isinstance(v, dict):
+            result[k] = _deep_merge(result[k], v)
+        else:
+            result[k] = v
+    return result
+
+
+def _write_defaults():
+    try:
+        import tomli_w
+        with open(CONFIG_PATH, "wb") as f:
+            tomli_w.dump(DEFAULTS, f)
+    except ImportError:
+        with open(CONFIG_PATH, "w") as f:
+            f.write("# tüit Transkriptor config\n\n")
+            f.write('[ollama]\nbase_url = "http://localhost:11434"\nmodel = "gemma3:12b"\n\n')
+            f.write('[whisper]\nmodel = "large-v3"\nlanguage = "de"\ndevice = "auto"\n\n')
+            f.write('[server]\nport = 8765\n\n')
+            f.write(f'[output]\npath = "{DEFAULTS["output"]["path"]}"\n')
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/test_config.py b/tests/test_config.py
new file mode 100644
index 0000000..726f542
--- /dev/null
+++ b/tests/test_config.py
@@ -0,0 +1,25 @@
+import os
+import tempfile
+from unittest.mock import patch
+
+
+def test_config_loads_defaults():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        cfg_path = os.path.join(tmpdir, "config.toml")
+        with patch("config.CONFIG_PATH", cfg_path):
+            import importlib, config
+            importlib.reload(config)
+            cfg = config.load()
+            assert cfg["ollama"]["model"] == "gemma3:12b"
+            assert cfg["whisper"]["model"] == "large-v3"
+            assert cfg["server"]["port"] == 8765
+
+
+def test_config_creates_file_on_first_run():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        import importlib, config
+        importlib.reload(config)
+        cfg_path = os.path.join(tmpdir, "config.toml")
+        with patch("config.CONFIG_PATH", cfg_path):
+            config.load()
+            assert os.path.exists(cfg_path)