# Lichess — The Forever Free Open Source Chess Server

> A full-featured online chess platform written in Scala, serving millions of games daily with no ads, no premium tiers, and completely open source.

## Install

Save in your project root:

# Lichess — The Forever Free Open Source Chess Server

## Quick Use
```bash
git clone --recursive https://github.com/lichess-org/lila.git
cd lila
./lila # requires sbt, MongoDB, Redis
```

## Introduction
Lichess is a non-profit, ad-free online chess platform that handles millions of games per day. Built in Scala on the Play Framework, it demonstrates that a complex real-time web application can be fully open source while competing with commercial alternatives.

## What Lichess Does
- Hosts real-time chess games with multiple time controls (bullet, blitz, rapid, classical)
- Provides puzzles, studies, analysis boards, and tournament systems
- Integrates Stockfish for server-side game analysis available to all users
- Offers a comprehensive REST and WebSocket API for third-party apps
- Supports team leagues, simultaneous exhibitions, and Swiss/Arena tournaments

## Architecture Overview
Lichess runs on the Play Framework (Scala) with MongoDB as the primary datastore and Redis for caching and pub/sub. Real-time game communication uses WebSockets routed through a Rust-based service called lila-ws. The Fishnet distributed computing network offloads Stockfish analysis across volunteer machines. The frontend is TypeScript with Snabbdom for reactive DOM updates.

## Self-Hosting & Configuration
- Requires JDK 21, sbt, MongoDB 6+, Redis 7+, and Node.js for asset compilation
- Use the `lila-docker` repository for a containerized development setup
- Configure via `conf/application.conf` for database URLs, ports, and feature flags
- Fishnet (analysis) and lila-ws (WebSocket) are separate services to deploy
- Development mode auto-reloads on Scala source changes via sbt

## Key Features
- Entirely free with no ads, subscriptions, or pay-to-win features
- Sub-100ms move latency through optimized WebSocket infrastructure
- Built-in opening explorer with millions of master and Lichess games
- Accessibility-first design with screen reader support and keyboard navigation
- Transparent Glicko-2 rating system with public rating distribution data

## Comparison with Similar Tools
- **Chess.com** — commercial with ads and premium tiers; Lichess is fully free and open source
- **Scid** — desktop-only database tool; Lichess is a full online multiplayer platform
- **PyChess** — smaller community, fewer features; Lichess has a much larger player base
- **en-croissant** — local analysis GUI; Lichess provides cloud analysis and multiplayer

## FAQ
**Q: How does Lichess sustain itself without ads?**
A: Through patron donations. The non-profit model keeps costs low with efficient infrastructure.

**Q: Can I use the Lichess API for my own app?**
A: Yes, the API is free and well-documented. Rate limits are generous for authenticated requests.

**Q: Is self-hosting practical for a club or school?**
A: Yes, though it requires several services. The Docker setup simplifies local deployment.

**Q: What languages is Lichess available in?**
A: Over 80 languages via community translation on Crowdin.

## Sources
- https://github.com/lichess-org/lila
- https://lichess.org/api

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Source: https://tokrepo.com/en/workflows/asset-41629773
Author: AI Open Source