Chess Opening Trainer: Drills

Chess Opening Trainer turns the chess openings you actually play into a personal repertoire you can drill from memory. Build each line on a real board, attach a note to any move, and train until the first ten moves feel automatic, whether you play the London System, the Ruy Lopez, the Italian Game, the Caro-Kann, the Queen's Gambit Declined or the Sicilian Najdorf.

A chess study and opening prep tool for club players: your own lines, your own notes, and your weakest variations first.

BUILD YOUR REPERTOIRE
• Start as White or Black and play each line on the board. Only legal moves are accepted, so every saved line is real chess theory, never a typo.
• Paste a move list (1. e4 e5 2. Nf3 ...) or import a PGN file to build faster.
• Tap any move to attach a note: the plan, the pawn break, the trap you are setting. It appears in the drill exactly when you go wrong there.
• Starter packs give you a ready first set to drill: Sicilian Najdorf, Ruy Lopez, Caro-Kann, Italian Game, Queen's Gambit Declined and London System. Edit, extend or delete anything afterwards.
• Export a repertoire as a PGN file, or share a single line.

DRILLS FROM MEMORY
• The opponent's theory replies play automatically and you supply your own. Miss one and the book move is shown on the spot.
• Spaced repetition schedules every line like a flashcard: a miss brings it back sooner, a clean run pushes it further out, and a slip deep in a variation costs less than a miss at the start.
• Position-first mode drops you into a position mid-variation and asks for the theory move, with a replay of how you got there.
• Two misses in a row trigger a short replay before you try again.
• Transpositions are recognised, and positions answered two different ways are flagged so you can pick one.
• Optional reminders tell you when reviews are due.

SEE YOUR WEAK SPOTS
• Progress ranks every variation by mastery, weakest first, next to your day streak, mastered-line count and average mastery.
• A "Coming up" view shows what is due on which day, and lines are grouped by opening name.
• Repertoire Gaps lists every legal opponent reply your saved lines do not answer yet. It is worked out offline; you can optionally rank the gaps with AI, which only reorders them and never hides a legal reply.

AI COACH
After a wrong move, tap Ask AI Coach for a plain-language explanation of why it fails in that position and what the better idea is. It explains opening theory; it is not a chess engine or a titled coach, so double-check critical lines.

WHAT'S FREE
• One complete repertoire (White or Black; built by hand, from a starter pack or from a PGN) with unlimited drilling, spaced repetition, Progress, streak, notes, reminders and the offline gap tree.
• Your first 5 AI Coach explanations, plus up to 2 more a day by watching a short ad.
• 3 gap rankings per repertoire, and PGN export.
• The free version shows ads.

WHAT PRO ADDS
• Unlimited repertoires for White and Black.
• Unlimited AI Coach explanations and gap rankings.
• AI game analysis: paste one of your games as PGN and see where you left your theory.
• Cloud backup of your lines and reviews (restore on the same account), plus a weekly study plan built from that backup.
• No ads.

Pro plans and local prices are shown in the app before you buy. Subscriptions are billed through Google Play and renew automatically until you cancel them in Google Play > Subscriptions.

YOUR DATA
No account needed: start training as a guest. Your repertoire, drill history and streak are stored on your device. AI features ask for your permission first, then send only what they need (the position and moves, your saved move lists, or the PGN you paste) to our server, which passes it to a third-party AI model. Cloud backup uploads only when you tap Back up now (Pro). Signing in is optional.

Available in 10 languages, with light and dark themes.

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