Getting Started

mimi.js is a Node.js web framework with an Express-compatible API. It works with JavaScript and TypeScript — no build step needed.

Installation

npm install mimi.js

Requires Node.js 22.6 or later.

---

Hello World

Create server.ts:

import mimi from 'mimi.js';

const app = mimi();

app.get('/', (req, res) => {
  res.json({ message: 'Hello from mimi.js!' });
});

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

Run it:

node server.ts

Visit http://localhost:3000 — you'll get:

{ "message": "Hello from mimi.js!" }

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Your First Routes

req.params captures URL segments, req.query captures query string values:

import mimi from 'mimi.js';

const app = mimi();

app.get('/users', (req, res) => {
  res.json({ users: [] });
});

app.get('/users/:id', (req, res) => {
  res.json({ userId: req.params.id });
});

app.get('/search', (req, res) => {
  const { q = '', page = '1' } = req.query;
  res.json({ query: q, page: Number(page) });
});

app.post('/users', (req, res) => {
  res.status(201).json({ created: req.body });
});

app.listen(3000);

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Adding Middleware

Call app.use() before your routes:

import mimi, { json, cors, security, requestLogger } from 'mimi.js';

const app = mimi();

app.use(json());          // parse JSON bodies
app.use(cors());          // CORS headers
app.use(security());      // security headers
app.use(requestLogger);   // log requests

app.get('/ping', (req, res) => res.json({ ok: true }));
app.post('/echo', (req, res) => res.json(req.body));

app.listen(3000);

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Environment Variables

Variable	Required	Description
JWT_SECRET	Yes (for auth)	Secret key for signing and verifying JWT tokens
LOG_LEVEL	No	pino log level: trace, debug, info, warn, error (default: info)

# .env
JWT_SECRET=your-super-secret-key
LOG_LEVEL=info

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Next Steps

Topic	What you'll learn
Route Loader	Auto-load route files from routes/ — zero wiring
Routing	Parameters, chaining, async handlers, 404s
Middleware	All built-in middleware with full options
Error Handling	Custom error responses and setErrorHandler
Authentication	JWT generation, verification, protected routes
Database	MongoDB and SQLite adapters
Plugins	Extending the framework with plugins
Testing	Testing routes and middleware with vitest