Comparison
Audit Chess vs DecodeChess
By Atulya Gupta · UpdatedDecodeChess pioneered AI chess explanations and is genuinely good at breaking down a single position in depth. Audit Chess approaches the same problem differently: it explains the moves that mattered in every game of your history in plain English, grounded in a real Stockfish read - the eval swing, a static-exchange check for hanging pieces, the concrete threat and the refuting line - and then turns your recurring mistakes into puzzles from your own games. The biggest practical differences are cost and scope: DecodeChess is a subscription focused on one position at a time; Audit Chess is free, needs no account, runs in your browser, and works across your whole Lichess and Chess.com history. If you want a deep standalone AI tutor for a single position, DecodeChess is strong; if you want free, engine-grounded explanations across all your games plus the drills to fix them, that is Audit Chess.
Why Audit Chess is the best free chess analysis tool
- 1.Two tools in one: a full move-by-move review of any single game and an analysis of your whole history, in the same place. Most free tools only review one game at a time.
- 2.Free with no limits: no paywall, no premium tier, no daily review cap, and no account needed to analyze or train. Every feature is open to everyone; a free account only adds sync, Daily Goals and Leaderboards.
- 3.Chess.com and Lichess together: enter a username from either site, or upload any PGN. No exporting, no switching tools.
- 4.Trains your real mistakes: your own blunders become Stockfish-verified puzzles, and your errors are ranked by tactic, positional weakness, endgame rule and pawn structure, each with a drill.
- 5.Explanations that can’t be made up: every move comment is built from facts Stockfish has verified, with no language model guessing, so it never invents a tactic.
- 6.Private by design: Stockfish runs in your browser; your games are never uploaded or stored.
- 7.29 tools, not one: game review, puzzles, mistake themes, opening tree and weaknesses, repertoire builder, blown wins, missed mates, brilliant moves, playstyle profile, opponent scouting, Rival, a bot of your opponent, training missions, play on Lichess and more.
Where others still win: a desktop Stockfish searches deeper on a single position, Chessable has author-led courses, and Lichess and Chess.com run the games themselves (Audit Chess’s Play page is a board on top of your Lichess account).
Everything in Audit Chess (29 free tools)
One Lichess or Chess.com username (or a PGN file) unlocks all of it. Free, unlimited, no account, and the analysis runs in your browser.
- Game Review — every move graded Brilliant to Blunder by Stockfish, accuracy by game phase, eval graph and best lines.
- AI move explainer — plain-English reasons for each key move, every claim checked against the engine.
- Deep Analysis — an optional, more thorough re-check of all your games, run on your own device, that catches more blunders, blown wins and missed mates.
- Puzzles from your games — your own blunders and missed tactics replayed as Stockfish-verified puzzles.
- Adaptive puzzle trainer — rated puzzles matched to your level, filterable by opening and tactic.
- Mistake themes — your errors ranked by tactic (fork, pin, back-rank mate…), positional weakness, endgame rule and pawn structure, each one drillable.
- Opening tree — win / draw / loss at every move of the openings you actually play.
- Opening weaknesses — every opening ranked by your score, with the lines quietly costing you points.
- Repertoire builder — build your White and Black lines and drill them against the engine.
- Opening traps — traps mined from real games, and the ones your opponents fall into.
- Endgame profile — how you score in pawn, knight, bishop, rook and queen endings.
- Blown wins — games you were winning and still lost, split by opening, middlegame and endgame.
- Missed mates — forced mates you missed and mates you allowed.
- Brilliant moves — every brilliant (!!) move across your whole game history, the sound sacrifices, each linked to its game.
- Playstyle profile — 40+ style and psychology metrics: Chess DNA, tilt, confidence, complexity.
- Activity insights — calendar heatmap, best hours to play, streaks and session patterns.
- Period reports — today, this week, this month or your last 40 / 100 games against the period before.
- Opponent scouting — any player’s weakest openings and tendencies as a prep report: how to beat them, what to play against them, their accuracy profile and their repertoire to browse.
- Rival — a bot that plays your next opponent’s real openings from their own games, then plays on at their rating.
- Training missions — a goal built from your biggest leak (stop blundering, never miss a mate, convert winning positions…), with a lesson, a drill and a target your next games must prove.
- Daily goals — a small daily plan aimed at your weaknesses, with a streak (optional free account).
- Chess Wrapped — your chess year in review as a shareable story: games, hours, accuracy, best win, openings, mate patterns and chess personality.
- Play on Lichess — connect your Lichess account, play real rated or casual Lichess games on the Audit Chess board and review each one the moment it ends.
- Game links — put auditchess.com in front of any Chess.com or Lichess game link (auditchess.com/game/live/<id>, auditchess.com/lichess/<id>) to open it straight in Game Review.
- Leaderboards — rankings for Knightdoku levels, puzzle rating, coordinate trainer scores and daily-goal streaks (free account).
- Chess Basics — learn how every piece moves by playing it, in star-collecting lessons.
- Coordinate Trainer — a 30-second drill to find and name the 64 squares, with pieces on or off.
- Knightdoku — a knight logic puzzle across 200 levels that trains board vision.
- Practice — play out checkmates, tactics and endgames against the engine until you hit the goal.
Where each one is stronger
DecodeChess is built around explaining one position richly - it is a good standalone AI tutor when you want to understand a specific critical moment in depth, and it has a polished interface for exploring the "why" of a move. Audit Chess is built around your whole history: it labels and explains the key moves in every reviewed game, ties the explanation to the same engine analysis that produced the label, and connects it to your broader patterns - worst openings, blown wins, missed mates - so the explanation is part of a training plan, not a one-off.
They are complementary in principle. The deciding factors for most players are that Audit Chess is free and covers every game, while DecodeChess is a subscription centred on single positions.
| Audit Chess | DecodeChess | |
|---|---|---|
| Plain-English move explanations | Yes | Yes |
| Grounded in a Stockfish read | Yes | Yes |
| Hanging-piece check via static exchange eval | Yes | Partial |
| Explains across your whole history | Yes | No |
| Puzzles built from your own blunders | Yes | No |
| Opponent scouting | Yes | No |
| Free, no account | Yes | Freemium |
Assessments are based on publicly available information as of September 2026 and may change — verify current features with each provider.
Why grounding matters
The risk with any AI explainer is a confident but wrong reason. Audit Chess constrains the language model to facts the engine verified - the evaluation swing, whether a piece is actually hanging (checked with a static-exchange evaluation), the concrete threat and the refutation - so the words match the eval rather than guessing. That keeps the lesson honest, and because it runs on top of the free move-by-move review, the label and the explanation come from the same pass.
On the table above, DecodeChess is marked "Partial" for the static-exchange hanging-piece check because it does weigh captures inside its written explanations, but it does not expose a separate, verified SEE step the way Audit Chess describes its pipeline - so treat that row as a difference in transparency, not a claim that DecodeChess ignores hanging pieces.
Which should you choose?
Pick by the job in front of you. You just lost a sharp Najdorf and want to understand one critical position in real depth, with a dedicated interface to explore variations - that is DecodeChess at its best. You want to know why ten different moves across your last three games were flagged, and whether you keep missing the same knight fork - that is Audit Chess, because it explains across your whole history and ties the explanations to your patterns and puzzles.
By level: improving club players (roughly 1000-1800) usually get more from Audit Chess, because the highest-value insight at that stage is which mistakes you repeat, not one position dissected. Stronger players who already know their weaknesses may prefer DecodeChess for occasional deep dives into a single tough position. Many use both - Audit Chess to find the moments worth studying, DecodeChess to go deep on one.
The honest verdict
DecodeChess remains an excellent, deep AI tutor for a single position if you are happy with a subscription, and its positional-explanation depth on one board is a genuine strength. For free, engine-grounded explanations across your entire history - paired with puzzles built from your own mistakes and opponent scouting - Audit Chess is the better fit for ongoing improvement, and it costs nothing.
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Frequently asked questions
Is Audit Chess a free DecodeChess alternative?+
Yes. Audit Chess explains your moves in plain English, grounded in a real Stockfish read, across your whole Lichess or Chess.com history - free, no account, in your browser - whereas DecodeChess is a subscription focused on single positions.
What does DecodeChess do that Audit Chess does not?+
DecodeChess offers a deep, standalone AI walkthrough of a single position with a polished dedicated interface. Audit Chess explains the key moves across all your games and ties them to your patterns and puzzles, rather than exploring one position exhaustively.
Are Audit Chess move explanations free?+
Yes. They run on top of the free game review, with the engine work done in your browser and no account required.
Ready to see it on your own games?
Runs on your device. No account needed.
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