Router/Routing library: That gives multiple routes (alternative routes)

Hi there!

I was asking myself if there is a good routing software/library that returns multiple routes (a route and some alternative routes).

I looked up for OSRM and I just read that sometimes there is alternative route given if the length/time is pretty much the same and the routes differ enough.

Here is an example what I mean with "alternative routes". The screens are from Google Maps/Navigation and Scout GPS Nav (formerly Skobbler) on Android:

They both offer 3 possible routes.

Any suggestions for a router that offers multiple alternative routes, like let's say 3 or 4 routes on default?

Thanks in advance!