I'm currently building an API and am looking for a tool to allow me to monitor (in a GUI) and rate-limit usage. I've come across a few enterprise solutions including:
The Apigee enterprise plan is exactly what I'm looking for but plans start at $3000 / month which is out of my price range. The other solutions are all either too expensive or do not provide the solution I'm looking for.
This led me to look at some open source options including:
Varnish seems like a fairly complete solution; however, I would need to build a GUI to visualise the data.
My final option would to build a solution from scratch using EventMachine and ruby.