localtunnel

localtunnel creates a publicly accessible URL that forwards traffic to a developer’s local server, allowing easy testing and sharing without DNS configuration or deployment. It is invoked from the command line (e.g., `lt --port 8000`) or programmatically via its Node.js API, which returns a Promise or accepts a callback once a tunnel URL is assigned. The tool supports optional arguments such as a custom subdomain, alternative local hostnames, and HTTPS configuration, and it automatically reconnects if the local service restarts.

The command‑line interface is available through global npm installation, as a project dependency, or via Homebrew, and the generated URL remains active for the duration of the session, making it suitable for browser testing tools and external services that require a public callback endpoint. The tunnel instance emits events for request handling, errors, and closure, and provides a method to terminate the tunnel.

Localtunnel is open‑source under the MIT license, with server implementation hosted separately and client libraries available for other languages such as Go, C#, and Rust. It is a stable, core CLI tool for developers needing temporary public exposure of local services.