zpaq v0.01 Open source (C++) and Win32 executables, Feb. 15, 2009.
zpaq v0.02 adds E8E9 transform. Fully supports post-processing. Not compatible with v0.01. Feb. 19, 2009.
zpaq v0.03 modifies MIX, MIX2, IMIX to fix poor compression on large files. Not compatible with v0.02. Feb. 19, 2009.
zpaq v0.04 modifies train() and squash() for improved compression. Not compatible with v0.03. Feb. 21, 2009.
zpaq v0.05 modifies probability representation and mixer weights to prevent mixer overflow and to improve compression for highly redundant data. Not compatible with v0.04. Feb. 26, 2009.
zpaq v0.06 adds SHA1 checksums, replaces IMIX2 with ISSE. Not compatible with v0.05. Feb. 27, 2009.
zpaq v0.07 improves ISSE and bit-history state table. Not compatible with v0.06. Feb. 28, 2009.
zpaq v0.08 adds LZP transform and minor improvements. Not compatible with v0.07. Mar. 8, 2009.
zpaq v0.09 removes counters from ISSE and ICM to improve speed. Not compatible with v0.09. Mar. 9, 2009.
zpaq v1.00 (first level 1 compliant version) includes unzpaq1 candidate reference decoder. Simplified bit history tables. Not compatible with earlier versions. Mar. 12, 2009.
unzpaq 1.01 updates reference decoder comments and help message and fixes some VS2005 compiler issues. Compatible with 1.00. Apr. 27, 2009.
unzpaq 1.02 and zpaq 1.02 closes extracted files immediately after decompression instead of when program exits. Fixes g++ 4.4 warnings. Compatible with 1.00 and 1.01. June 14, 2009.
unzpaq 1.03 and zpaq 1.03 has a default compression mode (mid.cfg), supports compressing files in segments to separate blocks and extracting them as suggested in part 7 of the spec. Does not store paths by default. Does not extract to absolute paths by default. Some minor improvements. Sept. 7, 2009 (added zpaq.exe Sept. 8, 2009).
zpaq103b adds zpaqsfx 1.03, a stub for creating self extracting archives. No changes to zpaq or unzpaq. Sept. 14, 2009.
zpaq104 can list and extract from self extracting archives without running them. Added progress meter. zpaqsfx.exe stub is slightly smaller. unzpaq unchanged. Sept. 18, 2009.
zpaq105 removes built in x and p preprocessors and makes them separate programs called from config files with compile time postprocessor testing. Adds if-else-endif and do-while to ZPAQL. Many small changes. Sept. 28, 2009.
zpaq106 adds "ta" to append locater tags to allow ZPAQ streams to be detected when embedded in arbitrary data. Sept. 29, 2009.
zpaqsfx 1.06 self extracting archive stub is now separate from the ZPAQ distribution. Updated Sept. 29, 2009, posted Oct. 26, 2009. (Replaced by zpsfx in libzpaq 2.01)
zpipe v1.00, a simple streaming compressor, Sept. 30, 2009. Linux patch added Jan. 18, 2010.
zpaq107 adds config file parameters and fixes some bugs. From now on the specification and reference decoder are not included unless they change. Oct. 2, 2009.