Top 7 chess-variant Open-Source Projects

Fairy-Stockfish

1 556 7.9 C++

chess variant engine supporting Xiangqi, Shogi, Janggi, Makruk, S-Chess, Crazyhouse, Bughouse, and many more

Project mention: Do Bughouse engines exist? | /r/chess | 2023-04-22

Fairy-Stockfish supports bughouse https://github.com/fairy-stockfish/Fairy-Stockfish/releases
openingtree

6 361 0.0 JavaScript

Consolidated view of all your chess games from chess.com, lichess, grandmaster games or custom pgn.

Project mention: I have 600 elo, i have 1 week to beat my D&D GM with 1500 elo | /r/chess | 2023-07-04

If you know his account on any chess sites you can take a look at it on https://www.openingtree.com/ and find a line he plays that is bad for him, intentionally go for it and have some prep once you there.
InfluxDB

www.influxdata.com
sponsored

Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
liground

0 94 3.1 Vue

A free, open-source and modern Chess Variant Analysis GUI for the 21st century
chess-pieces

0 33 0.0

Chess, Janggi, Xiangqi, Sittuyin pieces and boards
FairyFishGUI

0 16 4.5 Python

Minimalistic chess variant GUI for Fairy-Stockfish, superseded by fairyground
chess-variant-stats

1 15 10.0 Python

Calculate game statistics for chess variants

Project mention: Spartan Chess is now available on Fairy Stockfish and Pychess! Rules refresher video here | /r/chessvariants | 2023-04-19

Using https://github.com/ianfab/chess-variant-stats, which is the code that was the basis for https://lichess.org/@/ubdip/blog/finding-the-value-of-pieces/PByOBlNB .
A.C.A.S

1 0 5.3 HTML

Moved to psyyke.github.io

Project mention: Advanced Chess Assistance System: A.C.A.S | /r/userscripts | 2023-07-08

I'm excited to finally publish my biggest project ever, A.C.A.S. It's an advanced chess assistance system, or in a not so subtle way, a chess cheat. (Note that I'm not advocating cheating, only use this against bots, seriously!)
WorkOS

workos.com
sponsored

The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.

NOTE: The open source projects on this list are ordered by number of github stars. The number of mentions indicates repo mentiontions in the last 12 Months or since we started tracking (Dec 2020). The latest post mention was on 2023-07-08.