Parchive (a contraction of parity archive volume set) is an open source software project that emerged in 2001 to develop a parity file format, as conceived by Tobias Rieper and Stefan Wehlus. These parity files use a forward error correction-style system that can be used to perform data verification, and allow recovery when data is lost or corrupted.

The project is currently administered by Ryan Gallagher (binerman), Roger Harrison (kbalore), Willem Monsuwe (monsuwe), and Stefan Wehlus (wehlus).

Parchive was written to solve the problem of reliably sending large files on Usenet.

Usenet newsgroups were originally designed for informal conversations and the underlying protocol, NNTP was not designed to transmit arbitrary binary data. Another limitation, which was acceptable for conversations but not for files, was that messages were normally fairly short in length and limited to 7-bit ASCII text.

Various techniques were devised to send files over Usenet, such as uuencoding and Base64. Later Usenet software allowed 8 bit Extended ASCII, which permitted new techniques like yEnc. Large files were broken up to reduce the effect of a corrupted download, but the unreliable nature of Usenet remained.