FastJet

A software package for jet finding in pp and e+e collisions. It includes fast native implementations of many sequential recombination clustering algorithms, plugins for access to a range of cone jet finders and tools for advanced jet manipulation.
Download Release of FastJet 3.5.0 (latest stable release), 22 May 2025 (release notes).
This version introduces a new CMake-based build system. Autotools will continue to be supported for the duration of the 3.5.x series.
This release also includes speed improvements for corner cases of the N2Plain strategy, compilation bug fixes in the D0RunIICone plugin, improved compatibility of the autotools build system with the Bourne shell and SISCone 3.1.1 (with its own CMake support). See the full release notes for details.
Latest stable release of fjcore (v3.5.0), 22 May 2025.
Lightweight access to the core FastJet functionality (PseudoJet, JetDefinition, ClusterSequence and Selector).
It consists of just two files, fjcore.hh and fjcore.cc, which can easily be included in 3rd party projects. Compile time: a few seconds. A fortran interface and basic examples are also included in the distribution. Download size: 75k.
Release of FastJet Contrib 1.101, 24 February 2025.
A package of contributed add-ons to FastJet. This release (see NEWS for details) adds two new contribs: GHSAlgo (1.0.0) and SDFPlugin (1.0.1). It also brings small fixes to the build system. Fastjet contrib 1.100 and later requires FastJet 3.4.1 or higher and allows for dependencies between contribs. FastJet contrib 1.047 and later requires C++11 support in the compiler (if using GCC's g++ it should be version 5.1.0 or later). Direct download.