iJuggle is a siteswap generator and animator (Siteswap is a mathematical notation for representing juggling patterns). For more information on siteswap notation, check out siteswap.org.
The generator is based off of Jack Boyce's J2 program and allows you to choose between a variety of options for generating siteswaps such as async/sync/passing notation, multiplexing, ground/excited states, and composites. It will also allow you to only list siteswaps that contain or exclude certain throws.
The animator is based off of JuggleMaster written by Ken Matsuoka and C++ified by Per Johan Groland. With it you can animate synchronous, asynchronous, and multiplexing patterns. It also allows you to specify juggling styles such as mill's mess, which you can mix with any siteswap.