Configuration

The mobile app needs the backend root URL — host and port only, without /api/v1. The generated OpenAPI client adds that prefix automatically.

Resolution order

src/constants/config.ts resolves the URL in this order:

1. expo.extra.apiUrl in app.json
2. EXPO_PUBLIC_API_URL environment variable
3. Fallback: http://macbook.local:8000

src/constants/config.ts

export const API_BASE_URL =
  (Constants.expoConfig?.extra?.apiUrl as string | undefined) ??
  process.env.EXPO_PUBLIC_API_URL ??
  'http://macbook.local:8000';

Option A — app.json (recommended for builds)

app.json

{
  "expo": {
    "extra": {
      "apiUrl": "https://your-api.example.com/"
    }
  }
}

After changing app.json, restart the Expo dev server so expo-constants picks up the new value.

Option B — environment variable

export EXPO_PUBLIC_API_URL=http://192.168.1.100:8000
npm start

Useful for per-developer overrides without committing local URLs.

API URL by environment

Environment	Example URL	Notes
Production (MobiTrendz)	https://mobitrendz.onrender.com/	Default in app.json
iOS Simulator	http://localhost:8000	Backend on same Mac
Android Emulator	http://10.0.2.2:8000	Maps to host localhost
Physical device (Expo Go)	http://<LAN-IP>:8000	e.g. http://192.168.1.42:8000
Android physical device	http://<LAN-IP>:8000	Same as above; ensure same Wi‑Fi

:::tip Finding your LAN IP On macOS: ipconfig getifaddr en0
On Linux: hostname -I | awk '{print $1}' :::

How requests are built

If API_BASE_URL is http://192.168.1.100:8000, a login call becomes:

POST http://192.168.1.100:8000/api/v1/login/access-token

Configured in src/api/client.ts:

src/api/client.ts

client.setConfig({
  baseUrl: API_BASE_URL,
  auth: async () => accessToken,
});

Android cleartext HTTP

app.json enables usesCleartextTraffic so HTTP (non-TLS) local backends work during development. Use HTTPS in production.

iOS local networking

NSAllowsLocalNetworking is set in infoPlist so the iOS simulator and devices can reach local HTTP servers.

Verify connectivity

1. Start your FastAPI backend (default port 8000).
2. Open http://<your-api-url>/api/v1/checkDBConnection in a browser on the same network.
3. Sign in from the app — network errors show the configured API_BASE_URL in the message (see src/lib/api-error.ts).