Monotone

Monotone is a free distributed version control system. It provides a simple, single-file transactional version store, with fully disconnected operation and an efficient peer-to-peer synchronization protocol. It understands history-sensitive merging, lightweight branches, integrated code review and 3rd party testing. It uses cryptographic version naming and client-side RSA certificates. It has good internationalization support.

Its feature include:

• Store multiple versions of files you are working on efficiently
• Transmit changes to files between you and your colleagues
• Merge changes you make with those your colleagues make
• Make notes about your opinion of the quality of versions of files
• Make decisions about using or ignoring versions, depending on the notes you receive from others