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Chess Ext
A browser extension that layers chess analysis helpers — move clocks, board coordinates, and in-page study notes — on top of lichess and chess.com.
started Jun 4, 2025updated Feb 11, 2026
stack:TypeScriptManifest V3Stockfish WASM
Chess Ext keeps the parts of online chess I actually train on visible: move counts, a per-move clock tracker, coordinates on demand, and study lines you can annotate without leaving the game tab.
Highlights
- Manifest V3 — MV2 is deprecated; writing this meant staying current with Chrome and Firefox extension APIs.
- Local analysis — a bundled Stockfish (WASM) worker analyses positions entirely in the tab. No position ever leaves the browser, which is also the privacy story.
- Site adapters — DOM adapters for lichess and chess.com mean one core engine, two thin shells.
The extension is a favorite scratchpad for clean module boundaries: the analysis engine, the DOM adapters, and the UI layer each know nothing about the other two.