CTK (Cell Tool Kit) is a library which provides portable and basic C/C++ APIs for parallel programming on the Cell/B.E. Processor. CTK is intended to improve software development productivity on the Cell/B.E., and provide variety of 'almost mandatory' APIs for programming on the Cell/B.E. The base-level APIs include SPE execution control, multi-core synchronization primitives, SPE overlay task primitives and several miscelaneous helper routines. CTK enables 'write once, run on any Cell machine', therefore Cell applications written on CTK can run on multiple Cell/B.E. platforms like Sony PS3, IBM Cell blade (either with Cell SDK 1.x or 2.x) and Toshiba Cell Reference Set.