Stockfish 16.1

Today, we have the pleasure to announce Stockfish 16.1. As always, you can freely download it at stockfishchess.org/download and use it in the GUI of your choice.

Don't forget to join our Discord server to get in touch with the community of developers and users of the project!

Quality of chess play

In our testing against its predecessor, Stockfish 16.1 shows a notable improvement in performance, with an Elo gain of up to 27 points and winning over 2 times more game pairs than it loses.

Update highlights

Improved evaluation

• Updated neural network architecture: The neural network architecture has undergone two updates and is currently in its 8th version.
• Removal of handcrafted evaluation (HCE): This release marks the removal of the traditional handcrafted evaluation and the transition to a fully neural network-based approach.
• Dual NNUE: For the first time, Stockfish includes a secondary neural network, used to quickly evaluate positions that are easily decided.

UCI Options removed

Use NNUE and UCI_AnalyseMode have been removed as they no longer had any effect. SlowMover has also been removed in favor of Move Overhead.

More binaries

We now offer 13 new binaries. These new binaries include avx512, vnni256, vnni512, m1-apple-silicon, and armv8-dotprod, which take advantage of specific CPU instructions for improved performance.
For most users, using sse41-popcnt (formerly modern), avx2, or bmi2 should be enough, but if your CPU supports these new instructions, feel free to try them!

Development changes

• Updated testing book: This new book, now derived exclusively from the open Lichess database, is 10 times larger than its predecessor, and has been used to test potential improvements to Stockfish over the past few months.
• Consolidation of repositories: Aiming to simplify access to our resources, we have moved most Stockfish-related repositories into the official Stockfish organization on GitHub.
• Growing maintainer team: We welcome Disservin to the team of maintainers of the project! This extra pair of hands will ensure the lasting success of Stockfish.

Thank you

The Stockfish project builds on a thriving community of enthusiasts (thanks everybody!) who contribute their expertise, time, and resources to build a free and open-source chess engine that is robust, widely available, and very strong.

We would like to express our gratitude for the 10k stars that light up our GitHub project! Thank you for your support and encouragement – your recognition means a lot to us.

We invite our chess fans to join the Fishtest testing framework, and programmers to contribute to the project either directly to Stockfish (C++), to Fishtest (HTML, CSS, JavaScript, and Python), to our trainer nnue-pytorch (C++ and Python), or to our website (HTML, CSS/SCSS, and JavaScript).

The Stockfish team