Treeory

Treeory goes after the most common opening problem below master level: not a lack of theory, but the same slightly wrong move played in fifty games without anyone noticing. Its free Opening Leak Card is the quickest way to find out whether you have one. Enter a Lichess or Chess.com username, wait a minute, and Stockfish returns the three repeated moves that cost the most, each with the evaluation, the stronger move, how many games it occurred in and your score after it. No account, no email.

The card is honest about how it works. A leak is a move played at least five times by move 15 that Stockfish 17.1 rates at least half a pawn below its best choice; the card says so, says engines misjudge sharp positions, and lists separately the dubious moves that are scoring well for you. That second list matters, because the headline ranking is pure engine. On one card we generated, the top leak was 2.f4 - the King's Gambit itself, at -0.9 - for a player scoring 53% with it. A gambit player should read the card as a list of what a strong opponent would punish, not a list of what to drop.

The paid side builds on the same idea. Connect an account and Treeory imports your games every night, grows a repertoire tree from the lines you and your opponents actually reach, flags engine-dubious branches, and drills them with spaced repetition on a 12-point mastery scale that decays when you stop practising. After each game it shows where you left the tree. That is the gap it fills: Chess Tempo's opening trainer and Listudy are free and solid, but you build the repertoire by hand; Chessable sells you someone else's; openingtree.com shows what you play but does not check it or quiz you on it.

The trainer is a 30-day free trial with no card, then $7.99 a month or $69.99 a year (the same figures in euros in the EU, plus VAT). After the trial only the Leak Card, settings and export remain, but every tree exports as PGN at any time, so a free month is not wasted even if you never pay. We ran the Leak Card on public accounts and read the terms, privacy policy and pricing; we did not create an account, so the trainer is described from the site rather than from our own repertoire.

The operator is a registered Bulgarian company with its number and address in the terms, and the privacy policy is unusually specific, including about the cards anyone can generate for any username. The product is young, web-only and English-only.

For a 1200-2000 player who plays mostly blitz and rapid online, run the Leak Card first. If it finds something real, the trial month is the right length to fix it.