Ngrok - Securely Exposing Your Local App to the Internet

Introduction

Imagine you’re building a web application on your local machine, and you want to demo it to a remote team member, test it on a mobile device, or connect it to a third-party webhook (like GitHub or Stripe). Normally, this would involve complex networking setup like configuring your router, firewall, and dynamic DNS.

Enter Ngrok — a tool that makes this ridiculously easy.

What is Ngrok?

• Ngrok is a tool that creates secure tunnels from the public internet to your local machine.

• It acts as a reverse proxy, forwarding traffic from a public URL to a port on your localhost.

• Ngrok enables you to:
  • Expose local web servers to the internet
  • Securely share your work-in-progress with others
  • Receive webhooks from third-party services
  • Debug and replay HTTP traffic
  • Test APIs and websites from anywhere

Use Cases of Ngrok

1. Webhook testing (Stripe, GitHub, Twilio, etc.)
2. Mobile app testing (connect to local APIs)
3. Remote demos and presentations
4. Cross-device development
5. Secure introspection with HTTPS tunnels
6. IoT device connectivity to local services

How to Install Ngrok

Step 1: Sign Up

• Go to https://ngrok.com/ and sign up for a free account. This will give you an authtoken, which is needed to use the service.

Step 2: Download Ngrok

• Ngrok is available for macOS, Windows, and Linux.

# For Linux/macOS:
wget https://bin.equinox.io/c/bNyj1mQVY4c/ngrok-stable-linux-amd64.zip
unzip ngrok-stable-linux-amd64.zip
sudo mv ngrok /usr/local/bin

• Or use the official installers for your OS.

Step 3: Connect Your Account

• Once installed, connect Ngrok to your account using your authtoken:

ngrok config add-authtoken YOUR_AUTHTOKEN_HERE

How to Expose a Local URL

• Let’s say you’re running a web server on http://localhost:5000.

• Start a tunnel:

    ngrok http 5000
  

• You’ll see output like this:

    Forwarding                    https://abcd1234.ngrok.io -> http://localhost:5000
  

• You can now share https://abcd1234.ngrok.io with anyone, and they’ll be able to access your local server!

Using a Static Domain (Custom Subdomain)

• Ngrok offers static domains for Pro plans and above.

• Example:

    ngrok http --subdomain=mydevapp 5000
  

• Output:

    https://mydevapp.ngrok.io -> http://localhost:5000
  

• Make sure your subdomain is available and your plan supports reserved domains.

Bonus Features

1. Inspect Requests

• Ngrok has a built-in dashboard:

http://127.0.0.1:4040

• It shows detailed request/response logs. Super helpful for debugging!

1. HTTPS Support

• Ngrok automatically provides HTTPS tunnels, even if your local server doesn’t support it.

1. Authentication

• Secure your tunnel with basic auth:

ngrok http -auth="user:pass" 5000

1. Ngrok Configuration File (~/.ngrok2/ngrok.yml)

• You can define tunnels in a config file for easier reuse:

authtoken: YOUR_AUTHTOKEN
tunnels:
  web:
    proto: http
    addr: 5000
    subdomain: mydevapp

• Start with:

ngrok start web

Security Considerations

• Ngrok tunnels are temporary by default, unless reserved.
• Treat shared URLs like passwords — anyone with the URL can access your service.
• Always protect sensitive endpoints with authentication or IP whitelisting.

Alternatives to Ngrok

• While Ngrok is popular, here are some alternatives:

Tool	Description
LocalTunnel	Open-source alternative to Ngrok
Expose	PHP-based tunneling tool
Cloudflare Tunnel	Free and secure from Cloudflare
Tailscale Funnel	Tunnels over WireGuard mesh