We Built an AI That Explains Chess Positions

After reviewing hundreds of my own chess games, I realized something frustrating. Stockfish can tell you that move 23 was a blunder with perfect accuracy. But it can't tell you why it was a blunder in a way that helps you not make the same mistake next time.

You know the feeling. You finish a tough game, see a massive red “??” on move 23, and think: “Cool, I blundered. But... why?” The engine says Nf5 was best. Great, but what about the attack you thought you had? The engine doesn't care. It gives you a negative number and moves on.

We thought that was broken. So my co-founder Arya and I built Chessiro Coach — an AI system that analyzes your games and explains threats, ideas, and concepts directly in the position. Not after the fact in a paragraph you have to read separately. Right there, on the board, in context.

What Chessiro Coach actually does

Most chess analysis tools label your moves — blunder, mistake, inaccuracy, good, best. That labeling is useful, but it's only half the picture. Knowing that your move was bad is step one. Understanding why it was bad is where learning actually happens.

Chessiro Coach is an interactive AI chess coach integrated directly into your game review. After Stockfish 18 analyzes your game, the AI Coach goes through each critical position and generates explanations you can actually learn from.

It explains the “why”

Instead of only labeling moves as “Blunder” or “Inaccuracy,” the coach explains the reasoning behind the evaluation:

• What threat you missed — the opponent had a discovered attack on your queen that you didn't see
• Which tactical or positional idea was important — the knight on d5 was untouchable and controlling key squares
• What move would have solved the problem — retreating the bishop to e2 kept your structure intact and defended the weak pawn
• What you should have been thinking about — in this type of position, you need to watch for back-rank threats before pushing your pawns

This is the kind of feedback a human coach would give you. The difference is that Chessiro Coach is available after every single game, not just once a week for an hour.

It decodes chess concepts in context

Chess is full of terminology that can feel abstract when you're learning. Terms like:

• Semi-open files — what they are, why they matter, and how to use them
• Absolute pins — why you can't move that piece and what to do about it
• Weak squares — squares your pawns can no longer control and why the opponent wants to put a knight there
• Overloaded pieces — when one of your pieces is defending two things and the opponent exploits it
• Pawn structure weaknesses — isolated pawns, doubled pawns, backward pawns, and why they matter in your specific position

Reading about these concepts in a textbook is one thing. Having them explained in the position where they actually appeared in your game is completely different. The concept clicks because you experienced it. You were in that position, you made a decision, and now you understand what you missed.

Ask the coach anything

Even after explanations, questions often remain. “But what if I had played Bc4 instead?” “Why can't I just take the pawn?” “What was my opponent's plan here?”

You can now ask these questions directly. No question is too basic. The AI coach will:

• Answer your question in plain language, not engine notation
• Show arrows and highlight squares on the board to illustrate the idea visually
• Walk through different variations so you can see what would have happened
• Explain follow-up scenarios — “if you play that, your opponent responds with this, and here's why that's a problem”

It's like having a patient chess teacher sitting next to you who never gets tired of your questions. That's the experience we're going for.

How accurate is it?

We're transparent about this: the AI coach gets it right about 75-80% of the time. It's been tested across thousands of positions and games, and we've found that it provides valuable insights in most situations — especially for players rated below 2200 on Chess.com.

The 20% where it's off usually involves very complex strategic positions where even human coaches might disagree. For tactical explanations, pattern recognition, and conceptual teaching, the accuracy is higher. For deep endgame subtleties or highly theoretical opening positions, it can occasionally oversimplify.

We think that's a fair tradeoff. An explanation that's right 80% of the time and available after every game is more useful for most players than a perfect explanation that only happens once a week during a paid coaching session.

It doesn't replace a human chess coach

We want to be clear about this. Chessiro Coach does not replace a professional human chess coach. A strong titled player who knows you, understands your thinking process, and can create a structured training plan over months — that's irreplaceable for serious competitive players.

But here's the reality: most chess players can't afford regular coaching. Sessions cost $30-80/hour, and consistent improvement requires regular review, not just one session a month. Chessiro Coach provides an avenue for the millions of players who want to understand their games better but don't have access to — or can't afford — a human coach.

Our goal was to create a powerful learning companion that explains ideas clearly and make it accessible to everyone. Not everyone can afford a GM coach. Everyone deserves to understand why they lost.

The more you use it, the better it gets

Chessiro Coach learns how you play over time. As you review more games, it starts to understand:

• Your common mistakes — do you keep hanging pieces in time pressure? Do you miss knight forks? Do you play too passively in the middlegame?
• Your strengths — maybe your endgame play is solid, or you consistently find tactical shots in open positions
• The patterns you miss repeatedly — if you keep falling for the same type of tactic, the coach will flag it more prominently

Over time, the coaching becomes more personalized to your specific playing style and weaknesses. It's not just generic advice — it's advice based on your games, your patterns, and your rating level.

How it works in practice

1. Play a game on Chess.com or Lichess (or upload a PGN)
2. Open Chessiro and your game is automatically synced
3. Run a game review — Stockfish 18 analyzes every move
4. Activate the AI Coach — it generates explanations for your mistakes and key moments
5. Ask questions — tap on any position and ask the coach what you want to know
6. Practice your mistakes — Replay Mistakes turns your blunders into targeted puzzles

The whole loop — play, review, understand, practice — takes 5-10 minutes per game. That's all it takes to turn a loss into a learning experience.

Try it yourself

Chessiro Coach is live now. The free plan includes 2 AI Coach sessions per week so you can experience it without paying anything. If you find it useful, Pro gives you unlimited coaching across all your games.

We built this because we were frustrated with the gap between what engines can evaluate and what humans can understand. If you've ever stared at a blunder symbol wondering what you were supposed to do differently, this is for you.

Try Chessiro Coach →