Free chess PGN analyzer
Paste or upload a PGN and get a full Stockfish 18 review of every move — mistakes and blunders marked, turning points found, and every one of them explained in plain English. Unlimited, with no daily cap.
Drop a PGN file here
Chess.com, Lichess, or any .pgn
or paste PGN
- Stockfish analysis
- Plain-English explanations
- No account needed
How free PGN analysis works
Step 1
Paste or upload your PGN
Drop a .pgn file or paste the notation from Chess.com, Lichess, or an over-the-board game you transcribed. Bullet, blitz, rapid or classical — any time control works.
Step 2
Stockfish 18 checks every move
The engine runs in your browser and scores the whole game, classifying each move from genius down to blunder and marking the moments where the evaluation swung.
Step 3
The coach explains what happened
Every turning point comes with a plain-English explanation of the threat you missed and the better plan — and you can ask follow-up questions about any position.
What the free analysis includes
The same review a signed-in player gets. Nothing here is held back for a paid plan.
Move classifications
Genius, smart, best, good, book, inaccuracy, mistake and blunder — graded on win probability, not raw centipawns.
Accuracy and estimated rating
A per-player accuracy score with the playing strength it implies, so you can compare both sides at a glance.
Evaluation graph
The shape of the game in one picture, with key moments marked so you can jump straight to where it turned.
Time graph
Both players' thinking side by side, each bar coloured by the quality of the move that came out of it.
Engine lines
Stockfish candidate moves with adjustable depth and line count, plus a view of the threats coming next.
Opening database
Over 2.9 million real games. See how often the position won, lost or drew, and which moves players chose next.
AI coach with board arrows
Ask about any move and get an answer drawn on the board, read aloud if you like, in any of 24 languages.
Recommended training
The themes you missed and the ones you handled well, each with a one-click way to practise it.
For a full walkthrough of each tool, read the new Chessiro game review, explained.
No game to hand? Analyze a classic
Over a hundred of the most famous games ever played, each one opening in the same review. A good way to see what the analysis looks like before you paste your own PGN.
The Opera Game
1858
Paul Morphy vs Brunswick & Isouard
Morphy's Opera Game made rapid development look like a cheat code, with every piece arriving before the defenders were ready.
Immortal Game
1851
Adolf Anderssen vs Lionel Kieseritzky
Anderssen's Immortal Game became the great emblem of Romantic chess, ending after both rooks and the queen were sacrificed.
Evergreen Game
1852
Adolf Anderssen vs Jean Dufresne
Evergreen Game gave Anderssen another attacking masterpiece, remembered for a forcing finish that still feels fresh.
Rubinstein Combo
1907
Georg Rotlewi vs Akiba Rubinstein
Rubinstein's famous queen sacrifice turned quiet piece coordination into a direct attack, with bishops and rooks doing the heavy work.
Lasker's Bishops
1889
Emanuel Lasker vs Johann Bauer
Lasker's double bishop sacrifice became a textbook attacking pattern, cracking open the king with clean, logical force.
Marshall Attack
1918
Jose Raul Capablanca vs Frank Marshall
Marshall arrived with deep Ruy Lopez preparation, but Capablanca absorbed the attack and turned defense into a smooth win.
Browse all classic chess games or read why the classics are the best way to test an analysis tool.
Chess PGN analyzer FAQ
What is a chess PGN analyzer?
A PGN analyzer reviews a chess game written in Portable Game Notation. Chessiro runs Stockfish 18 on every move, classifies each one from genius through blunder, marks the turning points, and explains the critical moments in plain English so you know what went wrong and what to play instead.
Is the Chessiro PGN analyzer free?
Yes, and unlimited. You can paste or upload a PGN and analyze chess games for free without creating an account, and there is no one-per-day cap. Signing in is optional and lets you save games to your dashboard and build training from your mistakes.
Can I analyze Chess.com or Lichess games?
Yes. Export the game as PGN from Chess.com or Lichess — or any chess app — then paste or upload it here. Chessiro accepts standard PGN from any source, including games you transcribed over the board.
Do I need an account to analyze a PGN?
No. Guests can analyze games immediately. An account is only needed if you want to save the game for later, track mistake patterns across games, or turn your errors into training puzzles.
What do I get after uploading a PGN?
Full move-by-move Stockfish 18 analysis, move classifications, an accuracy score with an estimated rating, an evaluation graph and a time graph with key moments marked, adjustable engine lines, an opening database of 2.9 million games, and plain-English explanations you can dig into with follow-up questions.
What chess engine does the analyzer use?
Stockfish 18, the strongest open-source chess engine available. It runs locally in your browser rather than in a server queue, which is why analysis starts immediately and why we can offer it unlimited and free.
Free game review
Every game has one moment where it turned
Paste the PGN and find out what it was. Free Stockfish 18 analysis with every mistake explained in plain English, unlimited and with no account required.
