CastleiPlay Stockfish
Five difficulty levels from Gentle to Maximum, optional clocks, hints, takebacks and custom start positions. The engine runs on your device, so there is no waiting for a server.
For Android
A little practice.
A stronger game.
Castlei is a private chess companion. Play the Stockfish engine at five levels, review your games, and drill tactics and opening lines. It works fully offline.
Coming soon to Google Play Ask for early access
- No account needed
- Stockfish on your device
- Your games stay on your phone
What you can do
Everything a serious practice session needs
Review your games
Every move is compared with the engine's best. An evaluation graph shows where a game turned, and moves are marked as inaccuracies, mistakes or blunders, plus missed or allowed forced mates.
Daily tactics
Thousands of puzzles from the open Lichess database, filtered by rating and theme, with hints and the full solution on request. They work offline, and you can add more packs.
Opening repertoires
Build your own lines, then drill them with spaced repetition at 1, 3, 7, 14 and 30 day intervals. Transpositions are recognised, and opening names appear as you play.
Your library
Import and export PGN, keep studies with variations, comments and arrows, search and filter your games, and mark favourites.
Private by design
Your games live in a local database. Sign in only if you want cloud backup. Crash, performance and usage reports are anonymous and can each be switched off.
A look inside
Calm, readable, made for the board
Castlei Plus
Free to use. One optional unlock.
Everything above is free. Castlei Plus is a one-time purchase, with no subscription, that adds automatic cloud backup. It is not available yet; this is what it will include.
| Cloud backup | Free | Plus |
|---|---|---|
| Back up your games on demand | Yes, latest copy | Yes |
| Automatic backup after finished games and daily | – | Yes |
| Previous versions kept | 1 | 5 |
| Export a backup file to your own storage | Yes | Yes |
| Everything else in Castlei | Free | Free |
Open source
Built on great open-source work
Castlei stands on the Stockfish chess engine, the Lichess puzzle and opening data, the dartchess rules library, Flutter, and many other projects, each under its own license. The full list is in the app under Settings → About → Open-source software. Source code for GPL-licensed components is available on request at andwatiian@gmail.com.
Questions?
Write to andwatiian@gmail.com. To remove your account and cloud data, see Delete your account.