diff --git a/nanobot/config/oauth_store.py b/nanobot/config/oauth_store.py
new file mode 100644
index 0000000..eb4ceff
--- /dev/null
+++ b/nanobot/config/oauth_store.py
@@ -0,0 +1,59 @@
+"""OAuth credential storage."""
+
+import json
+from pathlib import Path
+from typing import Any
+
+from nanobot.config.schema import OAuthCredentials
+
+
+class OAuthStore:
+    """Stores OAuth credentials in a JSON file."""
+
+    FILENAME = "oauth-credentials.json"
+
+    def __init__(self, config_dir: Path):
+        self.config_dir = config_dir
+        self.file_path = config_dir / self.FILENAME
+
+    def _load_all(self) -> dict[str, Any]:
+        """Load all credentials from file."""
+        if not self.file_path.exists():
+            return {}
+
+        with open(self.file_path, "r") as f:
+            return json.load(f)
+
+    def _save_all(self, data: dict[str, Any]) -> None:
+        """Save all credentials to file."""
+        self.config_dir.mkdir(parents=True, exist_ok=True)
+
+        with open(self.file_path, "w") as f:
+            json.dump(data, f, indent=2)
+
+        # Secure permissions
+        self.file_path.chmod(0o600)
+
+    def save(self, provider: str, credentials: OAuthCredentials) -> None:
+        """Save credentials for a provider."""
+        data = self._load_all()
+        data[provider] = credentials.model_dump()
+        self._save_all(data)
+
+    def load(self, provider: str) -> OAuthCredentials | None:
+        """Load credentials for a provider."""
+        data = self._load_all()
+        if provider not in data:
+            return None
+
+        return OAuthCredentials(**data[provider])
+
+    def delete(self, provider: str) -> bool:
+        """Delete credentials for a provider."""
+        data = self._load_all()
+        if provider not in data:
+            return False
+
+        del data[provider]
+        self._save_all(data)
+        return True
diff --git a/tests/test_oauth_store.py b/tests/test_oauth_store.py
new file mode 100644
index 0000000..93282b6
--- /dev/null
+++ b/tests/test_oauth_store.py
@@ -0,0 +1,55 @@
+"""Test OAuth credential storage."""
+import pytest
+import tempfile
+from pathlib import Path
+from nanobot.config.oauth_store import OAuthStore
+from nanobot.config.schema import OAuthCredentials
+
+
+@pytest.fixture
+def temp_store():
+    """Create store with temp directory."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        yield OAuthStore(Path(tmpdir) / ".nanobot")
+
+
+def test_save_and_load_credentials(temp_store):
+    """Should save and load OAuth credentials."""
+    creds = OAuthCredentials(
+        access_token="sk-ant-oat01-xxx",
+        refresh_token="rt_xxx",
+        expires_at=1234567890
+    )
+
+    temp_store.save("anthropic", creds)
+    loaded = temp_store.load("anthropic")
+
+    assert loaded is not None
+    assert loaded.access_token == creds.access_token
+    assert loaded.refresh_token == creds.refresh_token
+
+
+def test_load_nonexistent_returns_none(temp_store):
+    """Should return None for missing credentials."""
+    assert temp_store.load("nonexistent") is None
+
+
+def test_delete_credentials(temp_store):
+    """Should delete saved credentials."""
+    creds = OAuthCredentials(access_token="sk-ant-oat01-xxx")
+    temp_store.save("anthropic", creds)
+    assert temp_store.delete("anthropic") is True
+    assert temp_store.load("anthropic") is None
+
+
+def test_delete_nonexistent_returns_false(temp_store):
+    """Should return False when deleting missing credentials."""
+    assert temp_store.delete("nonexistent") is False
+
+
+def test_file_permissions(temp_store):
+    """Credentials file should have restricted permissions."""
+    creds = OAuthCredentials(access_token="sk-ant-oat01-xxx")
+    temp_store.save("anthropic", creds)
+    perms = oct(temp_store.file_path.stat().st_mode)[-3:]
+    assert perms == "600"