# localtunnel — Expose Your Localhost to the World Instantly

> localtunnel is a lightweight Node.js tool that assigns a publicly reachable URL to a service running on your local machine. It requires no DNS setup, no firewall changes, and no account sign-up, making it the fastest way to share a local dev server.

## Install

Save in your project root:

# localtunnel — Expose Your Localhost to the World Instantly

## Quick Use
```bash
npx localtunnel --port 3000
# Output: your url is: https://random-slug.loca.lt
```

## Introduction
localtunnel provides a public HTTPS URL that forwards to a port on your local machine. It is especially useful for testing webhooks, sharing in-progress work with teammates, and running quick demos without deploying to a server.

## What localtunnel Does
- Creates an HTTPS tunnel from a public URL to a local port in one command
- Supports custom subdomains so you can get a predictable URL
- Works behind NATs and corporate firewalls without router configuration
- Runs as a CLI tool or can be used programmatically via its Node.js API
- Allows self-hosting the tunnel server for teams that need a private relay

## Architecture Overview
localtunnel opens a connection to a remote relay server that listens for incoming HTTPS requests on a generated subdomain. When a request arrives, the server multiplexes it over the existing connection back to the client, which forwards it to the local port. The client maintains a pool of sockets to the relay for concurrent request handling.

## Self-Hosting & Configuration
- Install globally with `npm install -g localtunnel` or run via `npx`
- Self-host the server component using `localtunnel-server` for private relays
- Set a custom subdomain with `--subdomain myname` for a stable URL
- Configure the local host with `--local-host 192.168.1.x` if not localhost
- Supports `--print-requests` flag to log incoming request details

## Key Features
- Zero-config tunneling with a single CLI command
- Free public relay at loca.lt with HTTPS included
- Custom subdomains for stable, bookmarkable URLs
- Programmatic API for integration into build scripts and test runners
- Open-source server for self-hosting a private tunnel relay

## Comparison with Similar Tools
- **ngrok** — Feature-rich commercial tunnel with a generous free tier; localtunnel is simpler and fully open-source
- **Cloudflare Tunnel** — Requires a Cloudflare account; localtunnel needs no sign-up
- **Tailscale Funnel** — Mesh VPN approach; localtunnel is a lighter single-purpose tool
- **bore** — Minimal Rust tunnel; localtunnel adds subdomain support and a Node.js API

## FAQ
**Q: Is the public loca.lt relay free to use?**
A: Yes. The default relay is free with no sign-up, though it may have rate limits for heavy traffic.

**Q: Can I use localtunnel for production traffic?**
A: It is designed for development and demos. For production, self-host the server or use a dedicated tunnel service.

**Q: Does it support TCP or only HTTP?**
A: localtunnel is HTTP/HTTPS only. For raw TCP tunnels, consider tools like chisel or bore.

**Q: How do I get a consistent URL between restarts?**
A: Use the `--subdomain` flag to request the same subdomain each time, for example `lt --port 3000 --subdomain myapp`.

## Sources
- https://github.com/localtunnel/localtunnel
- https://theboroer.github.io/localtunnel-www/

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Source: https://tokrepo.com/en/workflows/a91e036f-4105-11f1-9bc6-00163e2b0d79
Author: AI Open Source