JPCSP is an open-source PlayStation Portable emulator. It requires Java Runtime environment to be installed.
It requires the Java Runtime Environment to be installed, which has a history of security issues. Because it uses Java, it is also much slower than PPSSPP.
The developers of JPCSP never intended for it to become a standard emulator. It was created to better understand the PSP's inner workings. Thanks to the JPCSP team, PPSSPP developed quickly and can play most of the PSP library. Both teams communicate and contribute with each other.