Deeper analysis. Honest feedback. No paywalls.
Stockfish 17.1 runs directly in your browser—unlimited, offline-ready, and free. Every feature is designed around one goal: helping you actually improve.
The story behind Chessomy
I built Chessomy because I got tired of analysis being treated like a subscription perk.
I used to rely on unlimited game review. When I cancelled, the limit came back instantly—and I realized I wanted something I could use anytime without paywalls, queues, or accounts.
So I built the tool I wished existed: Stockfish running locally in the browser, with offline-first support and zero server-side game storage. Your analysis stays on your device.
Chessomy is still a one-person project, and I use it every day—which means the details get refined constantly. But the core promise won't change: no limits, no paywalls, no nonsense—just a tool that helps you play better chess.
Built by Jeromy Mobley—Vancouver Island, BC. Feedback and bug reports are always welcome.
What makes Chessomy different
Unlimited local Stockfish
No cloud queues, no daily caps. Stockfish 17.1 runs on your device with depth presets you control.
Offline-first PWA
Cache once, analyze anywhere. Works on flights, trains, and spotty Wi-Fi.
Transparent accuracy
Open formula, clear move classifications. No mystery scores or hidden algorithms.
Blunder puzzles from your games
Turn your worst moments into targeted training. Puzzles from positions where you actually went wrong.
No account, no paywall
Full analysis, full features, completely free. Your games never leave your device.
Honest feedback
Built for improvement, not engagement. No streaks, no gamification traps, no sugarcoating.
How it works
Three steps. Everything runs in your browser.
Import games
Connect Chess.com or Lichess, or paste a PGN directly.
Analyze locally
Stockfish evaluates each position at the depth you choose. No cloud, no waiting.
Train the gaps
Convert blunders into puzzles and fix the patterns that cost you games.
Analysis transparency
No hidden algorithms. Here's exactly how Chessomy scores your games.
The accuracy formula
Each move gets an accuracy score based on centipawn loss (CPL)—the difference between the engine's best move and yours, measured in hundredths of a pawn. Small inaccuracies barely affect your score; large mistakes drop it fast.
Accuracy = 100 × e−0.0001 × CPL²This project is still growing
Chessomy gets better when players use it and speak up. If something's broken, tell me. If something's missing, suggest it. Your feedback shapes what comes next.
Feedback, bug reports, feature ideas, or just to say hi—everything gets read.