GraphHopper 
GraphHopper is a fast and memory efficient Java road routing engine released under Apache License 2.0. It is tuned towards road networks with OpenStreetMap data but can be useful for public transport problems as well.
Get Started & Contribute
Read through our wiki, how to contribute and sign up to the mailing list.
Please only email me directly if you need consultancy or can't explain your problem in the public.
There are subprojects to make GraphHopper working on Android or as a web application. Have a look into our live application
Features
- Written in Java
- Open Source
- Memory efficient and fast
- Highly customizable
- Works on the desktop, as a web service and offline on Android
- Well tested
- Very few dependencies, no hibernate, no spring