Lcore

A fast, lightweight, single-file Python WSGI framework with zero dependencies.
Inspired by the simplicity of Bottle.

Documentation • Getting Started • API Reference

Installation

uv add lcore          # uv (recommended)
pip install lcore     # pip

Quick Start

from lcore import Lcore

app = Lcore()

@app.route('/hello/<name>')
def hello(name):
    return {'message': f'Hello, {name}!'}

app.run()

Key Features

• Single file, zero dependencies drop lcore.py into any project
• Full WSGI compliance works with Gunicorn, uWSGI, Waitress, and 17+ server adapters
• Concurrency without async/await run under the gevent/eventlet server adapters and ordinary synchronous handlers get real concurrency for free, no code changes. Measured: 200 concurrent requests to a 0.2s handler took 2.07s on a 20-thread server, 0.58s under gevent. async def handlers are accepted too, but do not provide concurrency under WSGI Lcore warns at first use of any async route.
• 10 built-in middleware CORS, CSRF, sessions, security headers, compression, body limits, request ID, logging, proxy fix, timeouts
• Server-side sessions revocable logins with memory, SQLite or Redis backends, sign-out-everywhere, and active device listing
• Security primitives PBKDF2 password hashing, HMAC-SHA256 signed cookies, rate limiting
• Dependency injection singleton, scoped, and transient lifetimes
• Plugin system JSON serialization, template rendering, and custom plugins
• Request validation JSON body and query parameter validation with type checking
• Built-in test client unit test routes without starting a server
• 12 lifecycle hooks request start, auth, handler enter/exit, response build/send, and more
• Module mounting compose sub-applications with isolated routes and middleware

Full documentation at lcore.lusansapkota.com.np.

Performance

Benchmarked with 100,000 iterations × 3 runs per framework (best run recorded), single process, no I/O, measuring pure framework overhead:

Lcore processes 2.2x – 4.6x more requests per second than Flask across 7 test scenarios (plaintext, JSON, route params, middleware stack, 404 miss, multi-route dispatch, POST JSON). See the full benchmarks for details.

Run the benchmarks yourself:

pip install flask bottle
cd benchmarks && python benchmark.py --full

When NOT to Use Lcore

If your workload is primarily synchronous REST APIs, internal services, microservices with sync DB drivers Lcore is a strong fit. That includes high-concurrency I/O-bound workloads too, as long as they don't specifically need asyncio-native libraries: the gevent/eventlet server adapters give ordinary synchronous handlers real concurrency under slow I/O, with zero code changes.

License

MIT see LICENSE for details.

Built by Lusan Sapkota • Inspired by Bottle