Open Source
Source code is publicly available for anyone to inspect, fork, or contribute to.
Lichess
Free, open-source online chess platform with zero ads, zero paywalls, and a full suite of play and training tools.
Stockfish
The world's strongest open-source chess engine, used for analysis in virtually every major chess platform.
Leela Chess Zero
Open-source neural network chess engine trained through self-play, offering a distinctive style compared to classical engines.
Maia Chess
Human-like AI chess engine trained to predict human moves at specific Elo levels, ideal for realistic practice.
Lichess Database
Massive open dataset of all Lichess games available for free bulk download in PGN and other formats.
Syzygy Tablebases
Online interface to Syzygy endgame tablebases, giving perfect play information for all positions with up to 7 pieces.
Chess Programming Wiki
Comprehensive wiki covering all aspects of chess engine programming, from search algorithms to evaluation functions.
ChessDriller
Free, open-source opening repertoire trainer using spaced repetition, compatible with any PGN repertoire file.
eval.bar
Open-source chess analysis tool that visualizes evaluation trends and lets you explore your games with engine commentary.
PyChess
Free, open-source online chess server supporting over 60 chess variants alongside standard chess.
PlayStrategy
Open-source strategy game server supporting chess variants alongside draughts, Go, Backgammon, Othello, and more.
Chessmadra
Free, open-source chess training app with a clean interface for tactics, opening drills, and game review.
ShareChess
Free tool to create animated GIF, MP4, and WebM videos from a PGN game for sharing on social media.
Scid vs PC
Free, open-source chess database and analysis GUI for Windows, macOS, and Linux with full engine support.
ChessX
Free, open-source cross-platform chess database and PGN viewer with a clean interface for game management.
Lichess for Schools
Free classroom tool built into Lichess, letting teachers create classes, assign students, and run school tournaments.
Chess Game Analysis
Free open-source tool to download and analyze your games from Lichess or Chess.com with Stockfish in the browser.
LucasChess
Free, feature-rich offline chess training software with engines, tactics, openings, and a unique competition system.
Lichess Forum
The community discussion forum of Lichess, covering chess improvement, platform features, and general chess topics.