How Reverse Proxies Work: The Complete Guide to Understanding and Using Tunneling Services Like Ngrok

Table of Contents

• What Is a Reverse Proxy?
• Forward Proxy vs Reverse Proxy: Understanding the Key Differences
• How Reverse Proxies Work: A Step-by-Step Breakdown
• Why Developers Need Reverse Proxies
• Common Use Cases for Reverse Proxy Services
• Popular Reverse Proxy Solutions
• InstaTunnel: The Superior Alternative to Ngrok
• Setting Up Your First Reverse Proxy Tunnel
• Best Practices for Using Reverse Proxies
• Security Considerations
• Conclusion

What Is a Reverse Proxy?

A reverse proxy is a server that sits between client devices (like web browsers) and backend servers, acting as an intermediary for requests from clients seeking resources from servers. Unlike a traditional proxy server that represents clients when making requests to servers, a reverse proxy represents the server when receiving requests from clients.

Think of a reverse proxy as a helpful receptionist at a large office building. When visitors arrive, they don’t go directly to the person they want to meet. Instead, they speak to the receptionist, who then directs them to the right office or handles their request appropriately. Similarly, when internet users want to access your web application, they connect to the reverse proxy first, which then forwards their requests to your actual server.

This concept becomes particularly powerful in development scenarios where you need to expose your local development server to the internet temporarily. Services like Ngrok, InstaTunnel, and others use reverse proxy technology to create secure tunnels from the public internet to your local machine.

Forward Proxy vs Reverse Proxy: Understanding the Key Differences

Before diving deeper into reverse proxies, it’s essential to understand how they differ from forward proxies, as this distinction often confuses newcomers.

Forward Proxy

A forward proxy acts on behalf of clients (users) when making requests to servers. When you use a VPN or corporate proxy to access the internet, you’re using a forward proxy. The server sees the proxy’s IP address, not yours.

Key characteristics of forward proxies: - Sits between clients and the internet - Hides client identity from servers - Often used for content filtering, caching, or bypassing geo-restrictions - Clients are aware they’re using a proxy

Reverse Proxy

A reverse proxy acts on behalf of servers when responding to client requests. The client thinks it’s communicating directly with the origin server, but it’s actually talking to the proxy.

Key characteristics of reverse proxies: - Sits between the internet and servers - Hides server details from clients - Used for load balancing, SSL termination, caching, and security - Clients are typically unaware of the proxy’s existence

How Reverse Proxies Work: A Step-by-Step Breakdown

Understanding the technical flow of reverse proxy communication helps developers appreciate why these tools are so valuable. Here’s what happens when a client makes a request through a reverse proxy:

Step 1: Client Request

A user enters a URL in their browser or an API client makes a request to what appears to be your server’s address. In reality, this address points to the reverse proxy server.

Step 2: Proxy Reception

The reverse proxy server receives the incoming request. It examines the request headers, URL path, and other metadata to determine how to handle it.

Step 3: Request Processing

The proxy applies any configured rules, such as: - Authentication checks - Rate limiting - SSL termination - Request modification or header injection

Step 4: Backend Forwarding

The proxy forwards the processed request to the appropriate backend server. In the case of development tunneling services, this backend server is your local machine running on localhost.

Step 5: Response Handling

Your local server processes the request and sends a response back to the reverse proxy. The proxy may modify this response (adding security headers, compressing content, etc.) before sending it back to the client.

Step 6: Client Response

The client receives the response, completely unaware that it came through a proxy server. From their perspective, they communicated directly with your application.

This entire process happens in milliseconds and enables powerful capabilities like exposing local development servers to the internet securely.

Why Developers Need Reverse Proxies

Modern web development presents several challenges that reverse proxies elegantly solve:

Local Development Limitations

When building web applications, developers typically run their code on localhost (127.0.0.1), which is only accessible from their local machine. This creates problems when you need to: - Test webhooks from external services - Share your work-in-progress with clients or team members - Test your application on different devices - Demonstrate features during video calls or presentations

Cross-Origin Resource Sharing (CORS) Issues

Modern browsers enforce strict CORS policies that can make local development challenging. Reverse proxies can help bypass these restrictions by serving your application from a proper domain with HTTPS.

Webhook Testing and Development

Many modern applications integrate with third-party services that use webhooks to send real-time notifications. These services need to reach your application over the internet, which is impossible with a localhost-only setup.

Mobile and Device Testing

Testing responsive designs and mobile-specific features requires accessing your development server from various devices. Without a reverse proxy, you’d need complex network configurations or deploy your code to test every change.

Common Use Cases for Reverse Proxy Services

Reverse proxy tunneling services have become indispensable tools for modern developers. Here are the most common scenarios where they provide immediate value:

Webhook Development and Testing

When integrating with services like Stripe, PayPal, GitHub, or Slack, you need to provide webhook URLs that these services can reach. During development, reverse proxy tunnels allow you to receive these webhooks directly on your local machine.

API Development and Testing

Building APIs often requires testing with external clients or sharing endpoints with frontend developers. Reverse proxies provide stable, accessible URLs for your local API servers.

Client Demonstrations

Nothing beats showing a live, working application to clients or stakeholders. Instead of deploying unfinished code, you can instantly share your local development server through a secure tunnel.

Cross-Device Testing

Modern web applications must work flawlessly across various devices and browsers. Reverse proxy tunnels let you test your localhost application on smartphones, tablets, and other devices connected to different networks.

IoT and Embedded Device Development

When developing applications that communicate with IoT devices or embedded systems, you often need these devices to connect back to your development environment. Reverse proxies make this connection possible without complex network configurations.

Microservices Testing

In microservices architectures, different services often need to communicate with each other. During development, reverse proxy tunnels can temporarily expose specific microservices for integration testing.

Popular Reverse Proxy Solutions

The reverse proxy tunneling space includes several popular options, each with different strengths and target audiences:

Traditional Reverse Proxies

• Nginx: The most popular web server and reverse proxy
• Apache HTTP Server: Long-standing web server with reverse proxy capabilities
• HAProxy: High-performance load balancer and reverse proxy
• Cloudflare: Global CDN with reverse proxy features

Development Tunneling Services

• Ngrok: The most well-known tunneling service
• InstaTunnel: Modern alternative with superior features
• Localtunnel: Open-source tunneling solution
• Serveo: SSH-based tunneling service

InstaTunnel: The Superior Alternative to Ngrok

While Ngrok pioneered the development tunneling space, InstaTunnel has emerged as a superior alternative, offering better features at a fraction of the cost. Here’s why InstaTunnel stands out as the best choice for developers:

Unmatched Value Proposition

InstaTunnel provides the same features as ngro