Who made this

Who

I'm Carlos Prieto, a software engineer and a club player rated around 1100. I built this because every review I could find graded me against the engine's best move. It would tell me I had missed a sacrifice that wins in nine moves, which was true and useless: nobody at my rating was going to find it, so knowing about it taught me nothing.

So the coach here grades against something else: what players at your own rating actually do in that position. A move most of them miss is a lesson, not a scolding. A move most of them find, and you didn't, is a habit worth fixing. That difference is the whole product.

It is a personal project rather than a company, which is why nothing here says "we".

How a review is put together

Nothing on this site is a language model's opinion about your chess. The chess is computed first, and the writing is only ever allowed to describe what was computed.

1. 1

   The engine looks at every position

   Stockfish evaluates the whole game, and every number is kept from the point of view of the side that moved, so "you were worse here" means exactly that.

2. 2

   A second model says what players like you do

   Maia is a neural network trained on human games at particular rating bands. It answers a question the engine cannot: how often do players at your rating actually play this move? That is where a line like "only 15% of players here find this" comes from.

3. 3

   The moments are chosen by rules, not by the writer

   The game is cut into blocks, and the facts of each block are collected, before a single word is generated. The shape of the story cannot be invented to fit a good sentence, because it already exists when the writing starts.

4. 4

   Only then is anything written down

   Every move, square and number in the commentary is checked back against that computation. A line claiming something the data does not support is thrown away and replaced with a plain mechanical one. That check is the part of this project I have spent the most time on.

The honest cost of working this way is that a review is sometimes dull. A sentence that would have read better but could not be backed does not get shown, and I would rather have the dull one.

The coaching is written in English, always, and translated afterwards behind a check that the translation carries exactly the same moves, squares and numbers as the English. A translation that fails that check is not shown: you get the English line in its place.

What it costs

Reading a review costs nothing and needs no account. Type a chess.com username, pick a game, read it.

The engine work is cheap and I do not ration it. The written coaching and the questions you can ask cost real money for every game, so an account comes with a monthly allowance of those rather than an unlimited supply. There is no paid tier: I would rather cap it honestly than sell something I am not sure I can support.

What it can't do

• It coaches rapid and blitz. Bullet games are imported so that your statistics are right, but never coached: at that speed the mistakes are mostly about the clock, and there is nothing useful to say about them.
• Without an account it reads chess.com only. Linking an account adds lichess.
• The picture across games, your habits, your profile, the weekly plan, is built from your last 200 games or twelve months, whichever comes first. Older games are not counted.
• It can still be wrong. The checks catch a claim that contradicts the computation; they cannot catch one that is merely unhelpful. If a review says something wrong about your game, tell me, that is the most useful thing you can send.

Getting in touch

If a review gets something wrong, or you want to say something about the product, I would like to hear it.

With an account, the feedback form in the menu is the fastest route: it reaches the same inbox.