JTransforms is the first, open source, multithreaded FFT library written in pure Java. Currently, four types of transforms are available: Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT), Discrete Sine Transform (DST) and Discrete Hartley Transform (DHT). The code is derived from General Purpose FFT Package written by Takuya Ooura and from Java FFTPack written by Baoshe Zhang. This version has been modified to daemonize threads and stop any application using the library waiting after execution has finished, and is based on revision 29 of the svn version of the code from 2014-05-18.