| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Dieter Dobbelaere
Date: Wed Feb 4 17:38:31 2026 +0100 Timestamp: 1770223111 Include threat weights in network hash calculation closes https://github.com/official-stockfish/Stockfish/pull/6583 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Disservin
Date: Wed Feb 4 17:34:11 2026 +0100 Timestamp: 1770222851 Fix clang-format complaints Somehow we forgot to add shm.h & shm_linux.h to the list of headers to be formatted. closes https://github.com/official-stockfish/Stockfish/pull/6591 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: anematode
Date: Wed Feb 4 17:32:48 2026 +0100 Timestamp: 1770222768 fix return type of vmovl_high_s8 also add -flax-vector-conversions=none to the build closes https://github.com/official-stockfish/Stockfish/pull/6587 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Disservin
Date: Wed Feb 4 17:29:42 2026 +0100 Timestamp: 1770222582 Restore development closes https://github.com/official-stockfish/Stockfish/pull/6581 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Joost VandeVondele
Date: Sat Jan 31 12:46:49 2026 +0100 Timestamp: 1769860009 Stockfish 18 Official release version of Stockfish 18 Bench: 2050811 --- Stockfish 18 Today, we have the pleasure of announcing Stockfish 18, a new major release. As always, you can freely download it at [stockfishchess.org/download][1] and use it as a drop-in replacement in the [GUI of your choice][2] to benefit from stronger play and more accurate analysis. Whether you can spare hours or days of CPU time, your help matters for the ongoing development of Stockfish. Find out how you can help at [stockfishchess.org/get-involved][3]. Join our [Discord server][4] to get in touch with the community of developers and users of the project! Quality of chess play In tests against Stockfish 17, this new release brings an Elo gain of up to [46 points][5], and wins [four times as many game pairs][6] as it loses. Quality improved throughout, including in [Fischer Random Chess][7]. Stockfish is stronger than any human, even when running on older or low-end hardware. On the highest-end hardware, where Stockfish can search over [500 million positions per second][8], it continues to [dominate chess engine tournaments][9]. Update highlights Next-Generation Evaluation This release introduces the SFNNv10 network architecture. The network’s input layer has been augmented with 'Threat Inputs' features as part of a massive community effort. These features allow the engine to 'see' which pieces are threatened more naturally, resulting in more accurate evaluations. Hardware and Performance Optimizations A key highlight is the new 'Shared Memory' implementation, which allows different Stockfish processes to share the same memory space for neural network weights. This makes it the most efficient version for cloud analysis and high-concurrency testing. Significant efforts have also been made to utilize hardware more effectively by adapting the code to make use of modern CPU instructions and refining how threads interact during a search. Search Improvements Stockfish 18 features a heavily refined search, utilizing 'Correction History' to dynamically adjust evaluations based on patterns found during the search itself. These and other refinements allow the engine to detect stalemates and evaluate fortresses significantly better than previous versions. A particularly rare issue, involving threefold repetition detection, en passant, and pins, was also fixed. Refactored Training Workflow The training of Stockfish's neural networks has transitioned to an automated and reproducible model. This new framework allows the project to employ standardized recipes to chain complex training stages together. This transition facilitates the training of networks using over 100 billion positions of [Lc0 evaluation data][10]. Thank you In this release in particular, we are deeply grateful to the contributors who shared their research and ideas to help develop the new threat-input network architecture. The Stockfish project builds on a thriving community of enthusiasts (thanks to 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 [14.6k stars][11] that light up our GitHub project. Thank you for your support and encouragement – your recognition means a lot to us. Programmers can contribute to the project either directly to [Stockfish][12] (C++), to [Fishtest][13] (HTML, CSS, JavaScript, and Python), to our trainer [nnue-pytorch][14] (C++ and Python), or to our [website][15] (HTML, CSS/SCSS, and JavaScript). The Stockfish team [1]: https://stockfishchess.org/download [2]: https://official-stockfish.github.io/docs/stockfish-wiki/Download-and-usage.html#download-a-chess-gui [3]: https://stockfishchess.org/get-involved/ [4]: https://discord.gg/GWDRS3kU6R [5]: https://tests.stockfishchess.org/tests/view/696a9e15cec152c6220c1d19 [6]: https://tests.stockfishchess.org/tests/view/696a9e4dcec152c6220c1d1b [7]: https://tests.stockfishchess.org/tests/view/696a9e83cec152c6220c1d1d [8]: https://openbenchmarking.org/test/pts/stockfish [9]: https://en.wikipedia.org/wiki/Stockfish_(chess)#Competition_results [10]: https://lczero.org/blog/2021/06/the-importance-of-open-data/ [11]: https://github.com/official-stockfish/Stockfish/stargazers [12]: https://github.com/official-stockfish/Stockfish [13]: https://github.com/official-stockfish/fishtest [14]: https://github.com/official-stockfish/nnue-pytorch [15]: https://github.com/official-stockfish/stockfish-web see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: anematode
Date: Wed Jan 28 20:28:27 2026 +0100 Timestamp: 1769628507 Fix compilation on BSD/macOS fixes github.com/official-stockfish/Stockfish/issues/6571 closes https://github.com/official-stockfish/Stockfish/pull/6572 No functional change see source |
| Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: anematode
Date: Thu Jan 22 19:15:17 2026 +0100 Timestamp: 1769105717 Make PGO builds deterministic again some environment dependent execution (e.g. pid) were being std::hash'ed, and net filenames put in unordered maps. Also uses sprintf instead of std::to_string. Depending on precise content, this could lead to different PGO'ed binaries. This is mitigated by using a basic hash function. This also fixes a potential issue in net filename generation, in cases where std::hash would use invocation dependent salt, which is not the cases today for typical std libraries. Closes https://github.com/official-stockfish/Stockfish/pull/6562 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: anematode
Date: Sun Jan 18 08:53:06 2026 +0100 Timestamp: 1768722786 use default signal handler after cleanup With the current setup, on Linux, SIGILL (and SIGSEGV/SIGBUS etc., in the case of a program bug) lead to no feedback if they occur after the signal handlers are installed, they just exit silently. By invoking the default signal handler, we can still get the appropriate feedback. This is particularly important for feedback if someone downloads the wrong SF binary and runs it on Linux. closes https://github.com/official-stockfish/Stockfish/pull/6554 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Robert Nurnberg @ elitebook
Date: Thu Jan 15 22:19:50 2026 +0100 Timestamp: 1768511990 update the WDL model This PR updates the internal WDL model, using data from 3.1M games played by the revisions since 44d5467. Note that the normalizing constant increases only moderately from 377 to 385. closes https://github.com/official-stockfish/Stockfish/pull/6549 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: anematode
Date: Thu Jan 15 22:17:14 2026 +0100 Timestamp: 1768511834 Skip munmap when exiting via a signal avoid munmap of memory when exiting via signal, which avoids side effects such as triggering asserts or (caught) segfaults while the process exists. closes https://github.com/official-stockfish/Stockfish/pull/6542 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Joost VandeVondele
Date: Thu Jan 15 22:13:26 2026 +0100 Timestamp: 1768511606 Fix integer overflow. scaledBonus can reach rather large values, which lead to an int overflow as detected anematode using ubsan. (see https://github.com/official-stockfish/Stockfish/issues/6505#issuecomment-3696988889) It can be fixed by scaling nominator and denominator appropriately, which doesn't change the bench, as long as there is no overflow. First overflow/bench change happens at depth 26 closes https://github.com/official-stockfish/Stockfish/pull/6540 Bench: 2050811 see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers Windows x64 + SSSE3 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Timothy Herchen
Date: Sun Jan 11 09:13:37 2026 +0100 Timestamp: 1768119217 Fix RelationCache on Windows 10 compiles Windows 10 is missing the GroupMasks and GroupCount members, this breaks compiles on Windows 10. Windows 11 builds, including the official ones, run fine on Windows 10/11. To support developers/testers on Windows 10, fallback conditionally to the Windows 10 struct definition. closes https://github.com/official-stockfish/Stockfish/pull/6538 No functional change see source |
| Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: KazApps
Date: Sun Jan 11 09:09:55 2026 +0100 Timestamp: 1768118995 Simplify make_index Refactor index LUT construction to simplify make_index. Passed STC Non-Regression: LLR: 2.93 (-2.94,2.94) <-1.75,0.25> Total: 62432 W: 16193 L: 16006 D: 30233 Elo +1.04 Ptnml(0-2): 189, 6950, 16764, 7111, 202 https://tests.stockfishchess.org/tests/view/6959985ad844c1ce7cc7eac8 closes https://github.com/official-stockfish/Stockfish/pull/6522 No functional change. see source |
| Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: KazApps
Date: Sat Jan 10 16:06:18 2026 +0100 Timestamp: 1768057578 Make enums unsigned Speed up by using unsigned enums. Passed STC: LLR: 2.98 (-2.94,2.94) <0.00,2.00> Total: 49248 W: 12894 L: 12568 D: 23786 Elo +2.30 Ptnml(0-2): 119, 5353, 13397, 5593, 16 https://tests.stockfishchess.org/tests/view/695e3e5002d0182a589fe965 closes https://github.com/official-stockfish/Stockfish/pull/6532 No functional change see source |
| Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: FauziAkram
Date: Sat Jan 10 15:47:11 2026 +0100 Timestamp: 1768056431 Simplify fail high reduction formula Passed STC: LLR: 2.97 (-2.94,2.94) <-1.75,0.25> Total: 165792 W: 42849 L: 42768 D: 80175 Elo +0.17 Ptnml(0-2): 512, 19499, 42800, 19566, 519 https://tests.stockfishchess.org/tests/view/695cdd95912b7ff140de60c2 Passed LTC: LLR: 2.95 (-2.94,2.94) <-1.75,0.25> Total: 80448 W: 20619 L: 20459 D: 39370 Elo +0.69 Ptnml(0-2): 47, 8693, 22596, 8829, 59 https://tests.stockfishchess.org/tests/view/695f7e84ca95f52e4b852536 closes https://github.com/official-stockfish/Stockfish/pull/6535 bench: 2050811 see source |
| Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: anematode
Date: Sat Jan 10 15:46:01 2026 +0100 Timestamp: 1768056361 Make shared history allocation aware of non-uniform cache access Although shared history has been successful overall, it led to some speed issues with large numbers of threads. Originally we just split by NUMA node, but on systems with non-unified L3 caches (most AMD workstation and server CPUs, and some Intel E-core based server CPUs), this can still lead to a speed penalty at the default config. Thus, we decided to further subdivide the shared history based on the L3 cache structure. Based on this test, the original SPRTs, and speed experiments, we decided that grouping L3 domains to reach 32 threads per SharedHistories was a reasonable balance for affected systems – but we may revisit this in the future. See the PR for full details. In an extreme case, a single-socket EPYC 9755 configured with 1 numa domain per socket, the nps increases from: Nodes/second : 182827480 to Nodes/second : 229118365 In many cases, when L3 caches are shared between many threads, or when several numa nodes are already configured per socket, this patch does not influence the default. This default setting can adjusted with the existing NumaPolicy option. closes https://github.com/official-stockfish/Stockfish/pull/6526 No functional change. see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Disservin
Date: Sat Jan 10 15:36:52 2026 +0100 Timestamp: 1768055812 Compiler Check Compiles and Runs Stockfish on all supported gcc & clang compilers. Only linux and avx2 currently. closes https://github.com/official-stockfish/Stockfish/pull/6533 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Disservin
Date: Sat Jan 10 15:34:37 2026 +0100 Timestamp: 1768055677 Fix Compiler Warning Only the one on line 158 is actually required but doesn't hurt to add constexpr where applicable here. Warning was "comparison of unsigned expression in '< 0' is always false" closes https://github.com/official-stockfish/Stockfish/pull/6530 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Disservin
Date: Sat Jan 10 15:33:36 2026 +0100 Timestamp: 1768055616 Fix Clang Tbprobe Miscompilation Recent changes to the Square enum (reducing it from int32_t to int8_t) now allow the compiler to vectorize loops that were previously too wide for targets below AVX-512. However, this vectorization which Clang performs is not correct and causes a miscompilation. Disable this vectorization. This particular issue was noticable with Clang 15 and Clang 19, on avx2 as well as applie-silicon. Ref: #6063 Original Clang Issue: llvm/llvm-project#80494 First reported by #6528, though misinterpreted. closes #6529 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Jakub Ciolek
Date: Tue Jan 6 12:08:08 2026 +0100 Timestamp: 1767697688 qsearch: prevent bestValue from going down The bestValue can sometimes go down. This happens 2% of the time or so. This fix stops it from decreasing. Failed gainer STC: LLR: -2.94 (-2.94,2.94) <0.00,2.00> Total: 146176 W: 37930 L: 37976 D: 70270 Elo -0.11 Ptnml(0-2): 480, 17422, 37366, 17304, 516 https://tests.stockfishchess.org/tests/view/6953be19572093c1986da66a Passed Non-regression LTC: LLR: 2.95 (-2.94,2.94) <-1.75,0.25> Total: 257796 W: 65662 L: 65683 D: 126451 Elo -0.03 Ptnml(0-2): 164, 28247, 72087, 28246, 154 https://tests.stockfishchess.org/tests/view/69554ff0d844c1ce7cc7e333 closes https://github.com/official-stockfish/Stockfish/pull/6520 fixes https://github.com/official-stockfish/Stockfish/issues/6519 Bench: 2477446 see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: anematode
Date: Tue Jan 6 12:02:37 2026 +0100 Timestamp: 1767697357 Network loading refactoring closes https://github.com/official-stockfish/Stockfish/pull/6523 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Syine Mineta
Date: Tue Jan 6 12:01:01 2026 +0100 Timestamp: 1767697261 Fix remote access bug across NUMA nodes Ensure that thread-local data is created within the correct NUMA context, so that thread stacks or thread-local storage are allocated to proper NUMA nodes. refs https://github.com/official-stockfish/Stockfish/issues/6516 closes https://github.com/official-stockfish/Stockfish/pull/6518 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: Joost VandeVondele
Date: Thu Jan 1 16:17:38 2026 +0100 Timestamp: 1767280658 Update of the year Happy New Year! closes https://github.com/official-stockfish/Stockfish/pull/6514 No functional change see source |
| Windows x64 for modern computers + AVX2 Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: mstembera
Date: Thu Jan 1 16:13:44 2026 +0100 Timestamp: 1767280424 Minor cleanup in full_threats.cpp closes https://github.com/official-stockfish/Stockfish/pull/6509 No functional change see source |
| Windows x64 for Haswell CPUs Windows x64 for modern computers Windows x64 + SSSE3 Windows x64 Linux x64 for Haswell CPUs Linux x64 for modern computers + AVX2 Linux x64 for modern computers Linux x64 + SSSE3 Linux x64 | Author: FauziAkram
Date: Thu Jan 1 16:12:35 2026 +0100 Timestamp: 1767280355 Replacing nested loops with a single range-based for loop closes https://github.com/official-stockfish/Stockfish/pull/6503 No functional change see source |