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Train on your own blunders

Your blunders are your best teacher.

KingChess analyzes your Chess.com and Lichess games, names the patterns behind your losses, and turns them into daily training until they stop showing up.

Your last 10 games · No signup needed · 12,000+ games analyzed

Game reviews with Bjorn · Named blunder patterns · Daily training plan

Training · From a real game

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What should you have played? · Move 31

White to move · 1 move

Drag a piece, or tap it to see its moves.

vs KnightSlayer64 · Blitz · Aug 2026

A real puzzle. Try it. Yours come from your own games.

Review your latest game

Enter your username. Coach Bjorn scores every move of your most recent game and shows what players at your level play. Free, no signup.

From the Discord

Players in the Discord, in their own words.

I am a 600 rated player and I used king chess ai for game review it is a great website. It helped me improve a lot and I would definitely recommend it to players at all levels specially beginners and intermediate

9/14/26, 10:53 AM

I am a 600 rated player and I used king chess ai for game review it is a great website. It helped me improve a lot and I would definitely recommend it to players at all levels specially beginners and intermediate

A 600 rated player, on game review.

Been using KingChess for reviewing games and honestly it's a pretty cool idea. I really like how it finds the mistakes from your actual games and turns them into puzzles instead of just throwing random puzzles at you. The site is clean and pretty easy to use. Would be nice to see more detailed explanations for mistakes and maybe some sort of progress/stat system in the future. Overall really solid project and definitely something I'd recommend to people trying to improve at chess. Good stuff bro

09:24

Been using KingChess for reviewing games and honestly it's a pretty cool idea. I really like how it finds the mistakes from your actual games and turns them into puzzles instead of just throwing random puzzles at you. The site is clean and pretty easy to use. Would be nice to see more detailed explanations for mistakes and maybe some sort of progress/stat system in the future. Overall really solid project and definitely something I'd recommend to people trying to improve at chess. Good stuff bro

Yoooooooooo definitely a dope website. Not only does it categorize your blunders into the opening, middlegame, and endgame, but it works with both Lichess and Chess.com too. I also love that you can analyze multiple games at once and, instead of just telling you that you blundered, it actually explains why the move was a mistake. It's certainly a creative way to review games.

8/17/26, 7:49 PM

Yoooooooooo definitely a dope website. Not only does it categorize your blunders into the opening, middlegame, and endgame, but it works with both Lichess and Chess.com too. I also love that you can analyze multiple games at once and, instead of just telling you that you blundered, it actually explains why the move was a mistake. It's certainly a creative way to review games.

It's actually really good ngl shows weaknesses with puzzles on how to fix it and shows you best moves I could of played and the continuation of them

8/27/26, 3:21 AM

It's actually really good ngl shows weaknesses with puzzles on how to fix it and shows you best moves I could of played and the continuation of them

Its a good website for reviewing your games and id probably recommend it.

9:00 PM

Its a good website for reviewing your games and id probably recommend it.

Coach Bjorn, the KingChess polar bear

Meet Coach Bjorn

He explains every blunder in plain English.

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Hung a piece

10...b5??

Coach Bjorn

You left your knight hanging on c6. After Bxc6, it's simply gone, and you're down about 3 points of material.

Even → Losing

Winning chances 48% → 13%

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Walked into a fork

10.a3??

Coach Bjorn

You're walking into a fork here. After Bg5+, your king and queen on h6 both get hit at once, and you can only save one of them.

Even → Losing

Winning chances 49% → 11%

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Gave back a winning position

28.Qxe5??

Coach Bjorn

You had a winning attack, but taking on e5 with your queen throws it away. Black recaptures with the queen, you take back with your rook, and the queens come off the board. Even though you win a pawn in the trade, your most dangerous piece is gone. An 83% winning position drops to a roughly level endgame where Black's rooks spring to life. When you are attacking a king, keep your queen on. Trading it off, even for a pawn, lets your opponent escape.

Winning → Even

Winning chances 83% → 52%

Real positions from players' games, in Bjorn's own words.

Full game review

He talks you through every move

Openings, trades, threats, the move you should have played, and how many players at your level find it. Every word is checked against the board before Bjorn says it.

A full game review: Coach Bjorn explains the blunder, the eval graph marks the turning points, and the move summary tallies both players

Nh5

Nh5 challenges the bishop on f4 and opens lines for the queen on d8. The game is level.

c4?

A gift. Their mistake lifted your chances from 59% to 72%. Bc6 is the way to cash it. It was well within reach at your level.

Be6??

Deep breath. Your winning chances fell from 56% to 30%. Be6 leaves the pawn on b7 to the bishop on f3. Nbd7 was the move.

Real lines from reviewed games. Bjorn speaks from board facts, so he can point at the punishing move, the piece you left behind, and the chance you let slip.

Your blunder personality

Bjorn names the habit behind your losses. This is his read on a real account.

Coach Bjorn

Coach Bjorn

on AuricRyan, Chess.com, last 152 games

The Cold Starter

The opening is your danger zone.

60 of your 210 blunders were shaky openings.

Move 5. Qd2 was played. Bd2 was the move.

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Why you lose

See the patterns behind your losses

Bjorn sorts your blunders by the tactic behind them and tells you where to start.

Overview

Blunders

Games

Skills

Coach Bjorn

Start here

Hung a piece 9 blunders · 18% of what your mistakes cost

You moved a piece to a square where it could simply be taken, or you moved the piece that was guarding another one. Two questions before every move. What was this piece defending, and what can capture it where it lands.

How they happen

Coach Bjorn

Most of your blunders miss a threat that was already there.

Missed a threat

38

Created the weakness

17

What went wrong

Hung a piece

9

Walked into a fork

6

Losing trade

4

Allowed a pin

3

Start here is free. The full breakdown is Premium.

The patterns return until they stick

FSRS spaced repetition, the scheduler behind the best flashcard apps, brings every blunder back just before you'd forget it. Two days, then eleven, then six weeks apart, until the move you'd have missed is the move you reach for. The habit your games name, walked into a fork, hung a piece, fell apart in the endgame, gets its own drills on the same schedule.

The app grades every solve

10 min

Missed it

15 min

Needed a hint

2 days

Solved it

8 days

Instant recall

No rating buttons. A wrong move or a reveal is a miss, a hint is hard, a clean solve is good, instant recall is easy.

Every puzzle carries a stability, roughly how long until you'd forget it, and comes back when your recall is about to drop below 90%. Right again after a longer gap and the interval grows. Miss it and it drops back. Past three months it's cleared. About ten minutes a day: twenty reviews and five new puzzles, your own blunders first.

Try it: say how the solve went

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Today

This week

Weeks

Months

Cleared

Say how the solve went, and watch how far out the puzzle goes.

None of this is our invention. It is how people learn a language and still have it years later, and how serious players already drill their openings. Here it is aimed at the moves that actually cost you games.

Or the opposite approach

Woodpecker mode cycles a fixed set against the clock, same puzzles every round, until you beat your time.

Simple, Affordable Pricing

Start free, upgrade when you're ready for more intensive training.

100+ players are already training on their own mistakes.

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Start drilling your blunders

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Spaced-repetition drills for 10 of your blunders

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Up to 10 games per generation

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Every mistake enters your drill rotation, no slot cap

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100 Coach Bjorn explanations a day, on puzzles and game reviews

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Career Report across your years of play

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Woodpecker sets on 65+ themes, mix them freely

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Up to 300 games per generation

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Reveal puzzle answers with hints

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Lichess engine analysis on any position

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Priority queue, faster puzzle generation

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Track up to 3 accounts per platform: your main, an alt, an old username

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