Is there a way to find out what app is using most of my bandwidth in windows

I have found several that measures total bandwidth but none that tells me bandwidth per application. Preferably with some history or logging.

I'm using Windows Server 2008 R2

Have you looked at the built in Resource Monitor?

You can filter per process, and see various metrics such as number of connections and bandwidth usage.

NetLimiter is what you're after. Not only does it allow you to view bandwidth usage per-application, but you can also limit certain connections. It also has various logging options and comes in a free, lite, and pro version.

NetLimiter is an ultimate internet traffic control and monitoring tool designed for Windows. You can use NetLimiter to set download/upload transfer rate limits for applications or even single connection and monitor their internet traffic.

Along with this unique feature, Netlimiter offers comprehensive set of internet statistical tools. It includes real-time traffic measurement and long-term per-application internet traffic statistics.

A caveat for all of these answers: if your machine has been infected with a rootkit, you may not see the offending process(es) at all. Rootkits can alter the kernel to remove processes from the OS's view. These bandwidth monitoring tools will then not see them.

You could run something like Wireshark on this machine and route all of its traffic through another device (perhaps another machine monitoring inbound traffic with Wireshark also). By comparing the difference in bandwidth reported by the two machines you could determine if there are processes consuming bandwidth which are hidden from the OS.

If you are troubleshooting an issue with high usage a quick wireshark capture should make it pretty obvious. You stand to learn quite a bit in the process also.

Wireshark