cfv is a utility to both test and create .sfv (Simple File Verify), .csv, .crc, .md5(sfv style), md5sum, BSD md5, sha1sum, and .torrent checksum verification files. It also includes test-only support for .par and .par2 files. These files are commonly used to ensure the correct retrieval or storage of data.
Jeremi is groupware software for realtime document sharing. It supports distributed work on different documents or files by different people or project groups. It offers an always-up-to-date view of the project and its files and coordinates the dependency of the actual file status and access to those files. Jeremi is written entirely in Java.
konspire is a searchable, distributed file-sharing system featuring resumable file transfers and fast, exhaustive substring searches of all hosted file names on the network. konspire is written using pure Java. Load from processing search requests is distributed throughout a dynamically connected network of servers. Several fault-tolerant features ensure system correctness and reliability.
Pysync has both a demonstration implementation of the rsync and related algorithms in pure Python, and a high speed librsync Python extension. The pure Python is not fast and is not optimized, however it does work and provides a simple implementation of the algorithm for reference and experimentation. It includes a combination of ideas taken from librsync, xdelta, and rsync. The librsync Python extension is less flexible and harder to understand, but is very fast.
python-fchksum is a module used to find checksums of files (or stdin). It supports md5, crc32, cksum, bsd-style sum, and sysv-style sum. The advantage of using fchksum over the Python md5 and zlib(.crc32) modules is both ease of use and speed. You only need to tell it the filename, and the work is done by C code.