Mainline is a personal chess training app that fixes the mistakes you actually make. Most chess tools are built for playing games or selling pre-made courses. Mainline is built for one thing: taking your real games, finding the specific patterns that cost you rating, and drilling them until they're gone.
Connect your Chess.com or Lichess account. Mainline runs the Stockfish engine over your games at depth 20 or higher and identifies the mistakes you make repeatedly, not one-off slips, but the patterns. Each is priced in rating points so you know what's actually holding you back. From there, Mainline builds a daily, spaced-repetition drill queue that trains those weaknesses out, with short guided lessons that explain the idea in plain English.
Every line, variation, and tactic in Mainline is engine-verified at Stockfish depth 20+ before it ships. Nothing is hand-guessed, and openings are ordered by real master-game frequency, not opinion. The result is a Duolingo-style daily habit (streaks, bite-sized sessions, spaced repetition) wrapped around genuinely rigorous content. You can see how it stacks up on the chess-app comparison pages.
Improving beginners to intermediates, roughly 800–1400 rating, who are tired of losing the same way. It covers openings, opening traps, tactics, middlegame plans, and endgames. New to the vocabulary? The chess glossary defines every term, and the frequently asked questions cover the rest.
You can play through a real opening or trap instantly, no account required. Connect a chess account to unlock personalized weakness analysis. Mainline runs in the browser and installs as an app on iOS and Android. Right now everything on Mainline is completely free.