SyWiCo is a tool for managing concurrent modifications of shared files between unconnected computers. It can be used as a synchronization tool relying on email. Its main design goal was for synchronizing the source code by email between developers, when the use of a source control software is not possible. The communication is stateless and reduced to a very small number of messages, typically 2 or 4. It does not create any files in the directories that it synchronizes, and leaves one participant free from dealing with merging and conflict resolution. This is not a tool to replace source control programs, as it provides no versioning.