High Quality Content by WIKIPEDIA articles! ZPAQ is a proposed open format for highly compressed data, mainly created by Matt Mahoney. It is designed so that new compression algorithms may be developed without breaking compatibility with older versions of ZPAQ-compliant decompression programs. ZPAQ uses a configurable context mixing algorithm (based on PAQ) and sandboxed post-processing code. ZPAQ uses a streaming data format that supports archives, single file compression, and memory to memory compression. Several ZPAQ compatible compression programs and configurations are available under the GPL license. There is also a public domain API in C++ providing compression and decompression services. The format is believed to be unencumbered by patents.