ngrok is a reverse proxy that creates a secure tunnel from a public endpoint to a locally running web service. ngrok captures and analyzes all traffic over the tunnel for later inspection and replay.

• Expose any http service behind a NAT or firewall to the internet on a subdomain of ngrok.com
• Expose any tcp service behind a NAT or firewall to the internet on a random port of ngrok.com
• Inspect all http requests/responses that are transmitted over the tunnel
• Replay any request that was transmitted over the tunnel

• Temporarily sharing a website that is only running on your development machine
• Demoing an app at a hackathon without deploying
• Developing any services which consume webhooks (HTTP callbacks) by allowing you to replay those requests
• Debugging and understanding any web service by inspecting the HTTP traffic
• Running networked services on machines that are firewalled off from the internet

ngrok has no runtime dependencies. Just download a single binary for your platform and run it. Some premium features are only available by creating an account on ngrok.com. If you need them, create an account on ngrok.com.

ngrok developer's guide