Device development and networking

The default form0.config.js starts Expo on the local network. A physical device must be able to reach the development computer and port 8081. Host firewalls, isolated Wi-Fi networks, VPNs, and container networking can prevent that connection.

Start through form0-cli

Use the application-server integration when working from the form0 CLI:

Code
form0 serve --app

The CLI reads the devServer block in form0.config.js. Full command behavior belongs to the app development server reference.

Advertise a public development URL

When LAN access is unavailable, set the configured environment variable in .env.local:

Code
FORM0_APP_PUBLIC_URL=https://your-development-domain.example

Start the tunnel separately, then run form0 serve --app. For one run, use --public-url https://your-development-domain.example.

The URL must serve the Expo manifest, bundle, assets, and WebSocket traffic directly. Browser interstitials and access-challenge pages break Expo clients. Never treat a development tunnel as a production deployment or place privileged credentials in the mobile bundle.

Use a development build for production-oriented work or custom native code. Expo Go is an optional learning and evaluation client when a compatible SDK build is available for the target platform.