Download FST4

FST4 is developed and published on GitHub. The repository is the complete distribution: the header-only library, the fst4 command-line tool, 51 ready-to-run demo configs, the bundled sample data sets with attribution, the user documentation and the verification suite.

Get the sources and build

Either clone the repository or unpack a release archive; the build is the same from there (the Usage page walks the first run, README.md in the package has the platform notes for Windows/MinGW, macOS, Linux and Visual C++):

git clone https://github.com/psomol/fst4.git
cd fst4
cmake -S . -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build --parallel --target fst4
./build/bin/fst4 --config demos/demo10.cfg

Requirements

• A C++17 compiler — GCC, MinGW-W64, or Visual C++ — and CMake 3.16+ for the CMake build (Visual Studio project setup without CMake is also documented in the package).
• No external libraries: the toolbox is header-only and dependency-free. Optional extensions: LibSVM (for the LibSVM-backed SVM wrapper; the native linear/RBF SVM wrappers need nothing) and Eigen (numerics cross-verification builds only). Neither is distributed with FST4; fetch instructions ship in the package.
• Developed and release-gated on Windows (MinGW-W64 g++), macOS (Apple clang, arm64) and Linux (GCC) — the byte-exact regression baseline is verified on all three.

License, in brief

• FST4 is Copyright © 2000–present UTIA, Institute of Information Theory and Automation, Czech Academy of Sciences, and is dual-licensed.
• It is free software under the GNU Affero General Public License, version 3 (the file LICENSE in the repository): anyone, including commercial users, may use, modify and redistribute it, provided that any modified version they distribute or make available over a network is released under the same license with its complete source code.
• Organizations that want FST4 in closed-source products without those obligations need a commercial license from UTIA; in case of interest, write to utia@utia.cas.cz. LICENSING.md in the repository explains both options and the contributor license agreement that every contribution requires.
• The software is provided “as is”, without warranty of any kind, as stated in the license.

Issues and contributions

Bug reports and feature requests are welcome as issues on the repository; anything else — cooperation ideas, commercial-license inquiries — goes through Contacts.

Previous versions

FST3 and FST1 remain available on the Legacy page.