Third-party notices

Last updated: 26 July 2026

Strong Squares is operated by Berg Capital ehf., Seltjarnarnes, Iceland. The Service includes the following third-party data and software.

Lichess puzzle database

Selected training positions are derived from the Lichess puzzle database. Lichess database exports are released under the Creative Commons CC0 1.0 Universal public-domain dedication. No endorsement by Lichess is implied.

Stockfish and Stockfish.js

The in-browser analysis engine uses Stockfish.js 18.0.8, a WebAssembly port of Stockfish. Stockfish and Stockfish.js are free software distributed under the GNU General Public License version 3.

The corresponding source is available from the Stockfish.js project and the official Stockfish project. Berg Capital ehf. will also provide a machine-readable copy of the corresponding source on request, at no charge beyond the reasonable cost of distribution. Write to support@strongsquares.com.

Stockfish and Stockfish.js are provided without warranty under the terms of the licence. Strong Squares is not affiliated with or endorsed by the Stockfish or Stockfish.js projects.