APIs Are the Backbone of Modern Apps
Every app you use talks to APIs. Your weather app fetches data from a weather API. Your payment processor hits a payment API. Understanding REST API design makes you a more valuable developer.
REST Design Principles
- Stateless: Server doesn’t remember previous requests
- Resources: Everything is a URL-addressable resource
- HTTP Methods: Use them correctly
- JSON: Standard exchange format
Proper HTTP Method Usage
| Method | Action | Idempotent | Example |
|---|---|---|---|
| GET | Retrieve | Yes | GET /api/posts |
| POST | Create | No | POST /api/posts |
| PUT | Replace | Yes | PUT /api/posts/1 |
| PATCH | Update | Yes | PATCH /api/posts/1 |
| DELETE | Remove | Yes | DELETE /api/posts/1 |
Build with Express.js
const express = require('express');
const app = express();
app.use(express.json());
const posts = [];
app.get('/api/posts', (req, res) => {
res.json({ data: posts, total: posts.length });
});
app.post('/api/posts', (req, res) => {
const { title, content } = req.body;
if (!title) return res.status(400).json({ error: 'Title is required' });
const post = { id: Date.now(), title, content, createdAt: new Date() };
posts.push(post);
res.status(201).json(post);
});
app.get('/api/posts/:id', (req, res) => {
const post = posts.find(p => p.id == req.params.id);
if (!post) return res.status(404).json({ error: 'Post not found' });
res.json(post);
});
app.listen(3000, () => console.log('API running on port 3000'));Error Handling
// Global error handler
app.use((err, req, res, next) => {
console.error(err.stack);
res.status(500).json({ error: 'Internal server error' });
});Production Checklist
- Version your API (/api/v1/)
- Rate limit to prevent abuse
- Validate all input data
- Use HTTPS in production
- Add authentication (JWT recommended)
- Document with Swagger/OpenAPI
- Log requests and errors