# nmrugg/stockfish.js

The Stockfish chess engine for web browsers

Repository: https://github.com/nmrugg/stockfish.js
Canonical: https://ross.abutalabs.com/products/stockfishjs
Language: C++
License: GPL-3.0
License Family: copyleft
Last push: 2026-06-15T17:43:57+00:00

## Health v2 (maintenance only)
Score: 72/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 87, release rhythm 38, longevity 100
- inputs: {"age_days": 4466, "days_push": 79, "days_rel": 203, "gap_med": null, "n_releases_24m": 1}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1193, forks 168 (observed 2026-08-28T04:03:56.614139+00:00)

## What it is
A WebAssembly and asm.js port of the Stockfish chess engine (currently version 18) that runs entirely in web browsers. It ships in multiple builds (multi-threaded, single-threaded, lite, and asm.js) to balance strength, size, and browser compatibility, and is used as Chess.com's in-browser analysis engine.

## Use cases
- add a chess engine to a web app
- run chess analysis in the browser
- build an online chess game with an AI opponent
- embed stockfish in a website
- client-side chess move evaluation without a server
- power a chess puzzle trainer in the browser

## When to choose
- you need a strong chess engine running fully client-side in a browser
- you want to avoid hosting a backend engine service
- you need multiple build sizes to trade strength for load time
- you want the engine behind Chess.com's analysis

## When to avoid
- you need a native-speed engine for server-side or desktop analysis
- your target browsers lack WebAssembly support and you cannot tolerate the weak asm.js fallback
- you cannot set cross-origin isolation headers and need maximum multi-threaded strength
- you are building a non-chess game AI

## Facets
- artifact type: library
- maturity: active
- function: game-engine, wasm, sdk
- domain: gaming-tools, web-development, cross-platform
- platform: browser, wasm
- tags: chess, stockfish, uci, webassembly, chess-engine, browser-game-ai, game-development, web-server

## Member repositories
- nmrugg/stockfish.js (main) score 72

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:56.614139+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:22:14.732494+00:00, confidence not recorded.
  - readme: https://github.com/nmrugg/stockfish.js (fetched 2026-08-28T04:03:56.614139+00:00, sha 413eaa8b65dd)
- Data as of 2026-08-30T08:39:29.467469+00:00.