LifJS ⚡

A blazingly fast, type-safe web framework for Bun. LifJS is built for Bun's native APIs, providing a modern developer experience without the bloat.

Key Features

• 🚀 Extreme Performance - Optimized radix tree routing and fast path extraction (no new URL() overhead).
• 🎯 Deep Type Safety - First-class TypeScript support with automatic param inference.
• 🔌 Middleware & Plugins - Robust middleware composition and a flexible plugin system.
• 📦 Zero Dependencies - Purely uses Bun's native APIs for a minimal footprint.
• 🛠️ Modern DX - Fluent context helpers, built-in CORS, logging, and rate limiting.

Quick Start

import { lifjs } from '@lifjs/core';

const app = lifjs();

// Simple text response
app.get('/', (ctx) => ctx.text('Hello LifJS!'));

// JSON response with route params
app.get('/users/:id', (ctx) => {
  const { id } = ctx.params;
  return ctx.json({ id, status: 'active' });
});

// Start the server (Bun native pattern)
export default {
  port: 3000,
  fetch: app.fetch
};

Installation

bun add @lifjs/core

Core Concepts

Application Setup

You can customize the base path and global error/not-found handlers.

import { lifjs } from '@lifjs/core';

const app = lifjs({
  basePath: '/api/v1',
  onNotFound: (ctx) => ctx.status(404).json({ error: 'Custom Not Found' }),
  onError: (err, ctx) => ctx.status(500).json({ msg: err.message })
});

Routing

Supports standard methods (get, post, put, delete, patch, all).

// Named parameters
app.get('/posts/:slug', (ctx) => {
  return ctx.text(`Reading ${ctx.params.slug}`);
});

// Wildcards (stored in ctx.params['*'])
app.get('/files/*', (ctx) => {
  return ctx.json({ path: ctx.params['*'] });
});

Sub-Routers

Organize your routes using createRouter and mounting them with app.route().

import { createRouter } from '@lifjs/core';

const auth = createRouter();
auth.post('/login', (ctx) => /* ... */);
auth.post('/signup', (ctx) => /* ... */);

app.route('/auth', auth);

Middleware

LifJS includes high-performance built-in middleware.

import { logger, cors, rateLimit, timeout } from '@lifjs/core';

app.use(logger());
app.use(cors({ origin: 'https://example.com' }));
app.use(rateLimit({ max: 100, window: 60000 }));

// Custom middleware
app.use(async (ctx, next) => {
  ctx.state.user = 'guest'; // State sharing
  const res = await next();
  // Modify response
  return res;
});

Context Helpers

The ctx object simplifies common tasks:

• Metadata: ctx.path, ctx.method, ctx.headers, ctx.query, ctx.params.
• Response: ctx.json(), ctx.text(), ctx.html(), ctx.redirect(), ctx.status(418).send().
• Body: await ctx.body() (auto-parses JSON/Form), ctx.formData(), ctx.blob().

Project Structure

lifjs/
├── packages/
│   └── core/           # Main framework source
├── examples/
│   ├── basic-api/      # Simple API usage
│   ├── blog-api/       # Models and routing
│   └── todo-api/       # CRUD with services
├── LICENSE             # MIT License
└── package.json        # Workspace configuration

Development

# Install dependencies
bun install

# Run tests
bun run test

# Build all packages
bun run build

License

MIT © 2026 LifJS Contributors