FastJet 3.1.0-beta.1, and its accompanying fjcore, were released on August 15, 2014.
Main improvement: speed gains between a factor of 1.5 to ten in the range between a few thousand and a few hundred thousand particles.
Release of FastJet Contrib 1.014, August 17, 2014

A package of contributed add-ons to FastJet. Release 1.014 updates JetCleanser to version 1.0.1, fixing a issue with C++11 compatibility, and adds the new SoftKiller contrib, version 1.0.0.
Release of FastJet 3.0.6, October 29, 2013 (release notes).

See these slides for a quick tour of the new features of FastJet 3. More ⇓ Download
Latest stable release of fjcore (v3.0.6), October 29, 2013.

Lightweight access to the core FastJet functionality (PseudoJet, JetDefinition, ClusterSequence and Selector). It consists of just two files, fjcore.hh and, which can easily be included in 3rd party projects. Compile time: a few seconds. Download size: 60k.