Yukari 💜

Yukari is a primarily xboard-protocol chess program. (UCI support exists, but xboard should be preferred if your GUI isn't from the stone age.)

how do I build it?

Yukari uses nightly Rust features to accelerate NNUE evaluation without the author's eyes bleeding, and cargo-pgo to automate a profile-guided optimisation run.

rustup component add llvm-tools
cargo install cargo-pgo
make

how strong is it?

• 2025.11.1: approximately 3550 CCRL 40/4
• 2025.4.1: 3510 CCRL 40/4; 3436 CCRL 40/40
• 2025.3.4: 3376 CCRL 40/4; 3329 CCRL 40/40
• 2025.2.4: 3081 CCRL 40/4; 3103 CCRL 40/40
• 2024.12.1: 2825 CCRL 40/4; 2824 CCRL 40/40

thanks to:

in no particular order:

• @Lunaphied who wrote the xboard protocol code
• @87flowers for motivating me to pick up Yukari after three years and for running lots of Yukari datagen
• @analog-hors for patiently debugging my transposition table code
• @dannyhammer for hosting and sharing the Toad OpenBench instance
• @Ciekce for guiding the NNUE implementation
• @JonathanHallstrom for running Yukari datagen
• Jim Ablett, for building binaries
• the Loftycord, for being amazing friends

sometimes you can teach an old wolf new tricks.