Vite's Proxy: The Development Feature You're Probably Overlooking

Let's talk about a practical Vite feature that doesn't get enough attention: the proxy configuration. If you're building SPAs that communicate with backend servers, this might save you some serious headaches.

The Development vs Production Disconnect

When you're building a modern web app, your production setup typically looks something like this:

User → Nginx → Frontend SPA
       ↓
       Backend API

Nginx (or similar) handles routing API requests to your backend while serving your frontend assets. But during development, you're running your frontend on one port and your backend on another.

This disconnect creates several issues:

• CORS errors
• Environment-specific code paths
• Inconsistencies between development and production

How Vite's Proxy Solves This

Vite's proxy configuration acts as a development-time stand-in for your production server setup. It intercepts specified requests from your frontend and forwards them to your backend server.

Here's a basic setup in your vite.config.js:

import { defineConfig } from 'vite'
import react from '@vitejs/plugin-react'

export default defineConfig({
  plugins: [react()],
  server: {
    proxy: {
      '/api': {
        target: 'http://localhost:3000',
        changeOrigin: true
      }
    }
  }
})

Practical Benefits

This simple configuration provides several immediate advantages:

1. Consistent code - Use the same API paths in development and production
2. No CORS configuration - Requests appear to come from the same origin
3. Realistic testing - Your local environment behaves more like production

Real-World Application

Consider a typical API request in your frontend code:

// This works identically in both environments
async function getUsers() {
  const response = await fetch('/api/users');
  return response.json();
}

During development, Vite intercepts the /api/users request and forwards it to your backend. In production, your web server does the same thing. Your frontend code remains unchanged between environments.

Beyond Basic Configuration

The proxy is powered by http-proxy, giving you additional options when needed:

server: {
  proxy: {
    '/api': {
      target: 'http://localhost:3000',
      changeOrigin: true,
      rewrite: (path) => path.replace(/^\/api/, ''),
      configure: (proxy, options) => {
        // Add authentication headers for development
        proxy.on('proxyReq', (proxyReq) => {
          proxyReq.setHeader('Authorization', 'Bearer dev-token');
        });
      }
    }
  }
}

When To Use This

This approach is particularly valuable when:

• Your app makes API calls to the same domain in production
• You're using relative URLs for API endpoints
• You want to minimize environment-specific code
• You need to test with realistic API interactions

The Takeaway

Vite's proxy configuration is a straightforward solution to a common development problem. It bridges the gap between development and production environments with minimal setup, letting you focus on building features rather than managing environment differences.

Next time you start a Vite project that needs to communicate with a backend, consider setting up the proxy configuration early. It's a small investment that pays off throughout the development process.