diff --git a/software/config.yaml b/software/config.yaml
index c647beb..e222048 100644
--- a/software/config.yaml
+++ b/software/config.yaml
@@ -1,7 +1,7 @@
 client:
   enabled: false
   url: null
-  platform: ''
+  platform: null
 
 llm:
   service: litellm
diff --git a/software/tests/test_config.py b/software/tests/test_config.py
new file mode 100644
index 0000000..2f6ff2d
--- /dev/null
+++ b/software/tests/test_config.py
@@ -0,0 +1,88 @@
+"""
+Tests for config.py module.
+"""
+
+from typing import Any
+
+from dotenv import load_dotenv
+
+from source.core.config import APP_PREFIX, Config, get_config
+
+
+def test_config_defaults() -> None:
+    config = Config()
+    assert not config.client.enabled
+    assert config.client.url is None
+    assert config.client.platform is None
+    assert config.llm.service == "litellm"
+    assert config.llm.model == "gpt-4"
+    assert not config.llm.vision_enabled
+    assert not config.llm.functions_enabled
+    assert config.llm.context_window == 2048
+    assert config.llm.max_tokens == 4096
+    assert config.llm.temperature == 0.8
+    assert not config.local.enabled
+    assert not config.server.enabled
+    assert config.server.host == "0.0.0.0"
+    assert config.server.port == 10001
+    assert config.stt.service == "openai"
+    assert config.tts.service == "openai"
+    assert config.tunnel.service == "ngrok"
+    assert not config.tunnel.exposed
+
+
+def test_config_from_dot_env(tmp_path, monkeypatch) -> None:
+    env_content = f"""
+    {APP_PREFIX}CLIENT_ENABLED=true
+    {APP_PREFIX}CLIENT_URL=http://localhost:8000
+    {APP_PREFIX}CLIENT_PLATFORM=mac
+    {APP_PREFIX}LOCAL_ENABLED=true
+    """
+    p: Any = tmp_path / ".env"
+    p.write_text(env_content)
+    monkeypatch.chdir(tmp_path)
+    load_dotenv(dotenv_path=str(p))
+
+    config = Config()
+    assert config.client.enabled is True
+    assert config.client.url == "http://localhost:8000"
+    assert config.client.platform == "mac"
+    assert config.local.enabled is True
+
+
+def test_config_sources_yaml(tmp_path, monkeypatch):
+    yaml_content = """
+    llm:
+        model: test
+        temperature: 1.0
+    server:
+        port: 8080
+    """
+    p: Any = tmp_path / "config.yaml"
+    p.write_text(yaml_content)
+    monkeypatch.setenv("01_CONFIG_FILE", str(p))
+
+    config = Config()
+    assert config.llm.model == "test"
+    assert config.llm.temperature == 1.0
+    assert config.server.port == 8080
+
+
+def test_config_apply_cli_args() -> None:
+    config = Config()
+    args: dict[str, Any] = {
+        "server": True,
+        "server_port": 8081,
+        "model": "test",
+    }
+    config = Config()
+    config.apply_cli_args(args)
+    assert config.llm.model == "test"
+    assert config.server.enabled
+    assert config.server.port == 8081
+
+
+def test_get_config() -> None:
+    config1: Config = get_config()
+    config2: Config = get_config()
+    assert config1 is config2
diff --git a/software/tests/test_init.py b/software/tests/test_init.py
new file mode 100644
index 0000000..8da2fa7
--- /dev/null
+++ b/software/tests/test_init.py
@@ -0,0 +1,12 @@
+from unittest.mock import patch
+
+from source import Config, config
+
+
+def test_config_loaded() -> None:
+    with patch("source.core.config.get_config") as mock_get_config:
+        mock_config: Config = config
+        mock_get_config.return_value = mock_config
+        from source import config as loaded_config  # pylint: disable=W0404,C0415
+
+        assert loaded_config is mock_config
diff --git a/software/tests/test_models.py b/software/tests/test_models.py
new file mode 100644
index 0000000..f25d25c
--- /dev/null
+++ b/software/tests/test_models.py
@@ -0,0 +1,47 @@
+from source.core.models import LLM, STT, TTS, Client, Local, Server, Tunnel
+
+
+def test_client_model() -> None:
+    client = Client()
+    assert not client.enabled
+    assert client.url is None
+    assert client.platform is None
+
+
+def test_llm_model() -> None:
+    llm = LLM()
+    assert llm.service == "litellm"
+    assert llm.model == "gpt-4"
+    assert not llm.vision_enabled
+    assert not llm.functions_enabled
+    assert llm.context_window == 2048
+    assert llm.max_tokens == 4096
+    assert llm.temperature == 0.8
+
+
+def test_local_model() -> None:
+    local = Local()
+    assert not local.enabled
+
+
+def test_server_model() -> None:
+    server = Server()
+    assert not server.enabled
+    assert server.host == "0.0.0.0"
+    assert server.port == 10001
+
+
+def test_stt_model() -> None:
+    stt = STT()
+    assert stt.service == "openai"
+
+
+def test_tts_model() -> None:
+    tts = TTS()
+    assert tts.service == "openai"
+
+
+def test_tunnel_model() -> None:
+    tunnel = Tunnel()
+    assert tunnel.service == "ngrok"
+    assert not tunnel.exposed