Legal
Enpasso is built on open source software. We are grateful to every project listed here.
GPL-3.0 Notice — Stockfish
Stockfish is distributed under the GNU General Public License v3.0. On the web, and as the Android app's fallback engine, Enpasso ships the official, unmodified stockfish.js WebAssembly build (version 18).
The Android app's native engine is compiled from the official Stockfish source at tag sf_16.1, via the Android NDK (ARCH=armv8 COMP=ndk), with no source modifications and no additional compile flags. The evaluation networks are embedded in the binary, as the upstream build does by default; the two networks are nn-b1a57edbea57.nnue and nn-baff1ede1f90.nnue, both also obtainable from github.com/official-stockfish/networks.
You may obtain the complete corresponding source code for both builds at github.com/official-stockfish/Stockfish. A copy of the GPL-3.0 license is available at gnu.org/licenses/gpl-3.0.html.
Chess engine powering position evaluation and best-move suggestions on the web and as the Android app's fallback. Distributed as the official, unmodified stockfish.js WebAssembly build.
Compiled from the official sf_16.1 source tag for the Android app's native engine, via the Android NDK. See the GPL notice below for the exact build recipe.
Chess move validation, PGN parsing, and game state management.
Interactive chessboard UI component.
Our puzzle library comes from the Lichess puzzle database, and Lichess accounts power game import. Lichess is free, open source, and ad-free — a great deal of what Enpasso offers rests on their work.
Chess piece SVG artwork by Colin M.L. Burnett, sourced from Wikimedia Commons, where the author offers it under GFDL, CC BY-SA 3.0, BSD or GPL; we use it under the BSD license, whose full text is served at /pieces/cburnett/LICENSE.txt. Served as size-optimised SVG with the artwork unchanged; the default piece set.
Chess piece SVG artwork, copyright 2015 Alexis Luengas. Used unmodified as an optional piece set; the license and copyright notice are served alongside the files at /pieces/chessnut/LICENSE.txt.
Chess piece SVG artwork by Maurizio Monge, as distributed by Lichess. Used unmodified as optional piece sets; the MIT license text is served alongside each set, e.g. /pieces/celtic/LICENSE.txt.
Chess piece SVG artwork by James Faure (https://creativecommons.org/licenses/by/4.0/). Files renamed to piece codes and size-optimised as distributed by Lichess; not otherwise modified. Used as an optional piece set.
Vector chess pieces by RhosGFX, dedicated to the public domain. Credit given with thanks; used as an optional piece set.
Flat silhouette SVG chess pieces by femrek, sourced from OpenGameArt.org. Public domain — no restrictions.
Additional open source packages are used as build-time or development dependencies. All packages are available via their respective npm registries with full license text included.