What is a localhost tunnel?

Your dev server listens on localhost, so only your computer can reach it. A tunnel gives it a public URL, so a phone, a teammate or a service like Stripe can reach it too, without you deploying anything.

How a tunnel works

Your computer usually can't accept connections from the internet: it sits behind a router or a firewall. So a tunnel works the other way round.

1. A small program on your machine opens an outgoing connection to a public server.
2. That server gives you a URL.
3. When someone opens the URL, the server sends the request down the connection that is already open.
4. The program passes it to localhost and sends the response back.

Nothing on your machine has to be reachable from the internet, and you don't change your router or firewall.

When you need one

• Webhooks: Stripe, GitHub and Slack can only call a public URL. See how to test webhooks on localhost.
• Testing on a real phone, over HTTPS and on any network. See how to test localhost on a phone.
• Showing work in progress to a teammate or a client before it is deployed.
• OAuth callbacks and other flows where another service has to reach you.

What to watch out for

The URL is public. Unless the tunnel has access control, anyone who has the link reaches your server. Don't expose databases, admin panels or anything holding secrets, and stop the tunnel when you are done.

Tunnels are for sharing work for a while. Use a real deployment for anything people depend on.

Vite and Next.js block requests from hostnames they don't know. Some tunnels make you add their domain to the config. hostc rewrites the headers instead.

Tunnel, port forwarding or deploy?

A tunnel isn't the only way to share your work. This guide compares a tunnel with a local IP, port forwarding and a preview deploy. In short, use a tunnel when the thing you want to show is running on your machine right now, and a deploy when people need it without you.

Common questions

Is a tunnel safe? The connection is encrypted between the visitor and the tunnel server, and your machine accepts no incoming connections. The risk is what you expose: everyone with the link can use your app, including any bug in it.

Does my computer have to stay on? Yes. The tunnel forwards to your machine, so the link stops working when it sleeps or the tunnel stops.

Is it the same as a VPN? No. A VPN joins your device to a private network. A tunnel publishes one local service to the internet.

Which tool should I use? See how to choose a localhost tunnel.

Try one

hostc is free and open source, with no account. If you are choosing between tools, compare the alternatives.