NetBalancer is a similar tool for Windows, with interesting functionality, but not free https://netbalancer.com

Glasswire is also interesting. Way smoother looking interface than any of the other stuff I've seen & there is a paid edition as well so they clearly put time into it.

Resource Monitor (resmon.exe) is built-in and will display per process up/down network usage. It does not have per-process graphs AFAIK.

It does, you just have to select them: http://i.imgur.com/begi54h.png (notice orange lines)

Honestly, Task Manager does the job for me. Windows 8 and up, it's great!

WFN is a free, open source alternative: https://wfn.codeplex.com/

There's also NetBalancer.com and NetLimiter.com with some similar functionality, though not open source.