Terms of use
Last updated 25 September 2026
By using MainLine you agree to these terms.
The service
MainLine helps you build and practise chess opening repertoires. It's provided free of charge, as is, without warranties of any kind. Opening statistics, engine evaluations and AI explanations can be wrong. Use your own judgement at the board.
Your content
Repertoires, notes and training data you create are yours. You give us permission to store and process them only to provide the service (for example, syncing between your devices).
Acceptable use
Don't abuse the service: no automated scraping, no attempts to overload it or get around rate limits, and no use that breaks the terms of Lichess or Chess.com. We may limit or suspend access to protect the service.
Third-party services
Features that use Lichess, Chess.com, Google or Groq depend on those services and their terms. We aren't responsible for their availability.
Free software
MainLine's source code is licensed under the GNU General Public License v3.0 or later. It includes chessground, chessops and Stockfish (GPL-3.0). Opening names come from lichess-org/chess-openings (CC0).
Liability
To the extent the law allows, we aren't liable for indirect or consequential losses, or for lost data. Keep a PGN export of anything important.
Ending
You can stop using MainLine and delete your data at any time from Settings. These terms may change; continued use after a change means you accept it.