OpenSync is an open source synchronization app. It can be used to sync data such as contacts, notes, and calendar tasks between your PC and your mobile device.
It’s a plastic app with several plugins available. OpenSync can be reused by many different applications; it’s geared for speed and flexibility. As such, it’s been built to be as modular as possible, so with the development of new formats and devices OpenSync can be adjusted and reused. What’s more, OpenSync is language neutral—meaning it’s extensible in other languages like python and java. It runs cross platforms. OpenSync is free to download. There’s a guide available to walk you through using it. You can also view the roadmap and timeline.
OpenSync.org In Their Own Words
“OpenSync is a synchronization framework that is platform and distribution independent. It consists of a powerful sync-engine and several plugins that can be used to connect to devices.
OpenSync is very flexible and capable of synchronizing any type of data, including contacts, calendar, tasks, notes and files.”
Why OpenSync.org It Might Be A Killer
OpenSync is ostensibly a useful application. It’s flexible and its open source nature will make it popular with tech types.
Some Questions About OpenSync.org
OpenSync doesn’t have a user friendly appeal. In fact, it looks complicated and therefore forbidding to most casual computer users. 
