On my team we use mitmproxy for observing traffic of our locally running instances of the backend for the project that I am working on.<p>Supposedly mitmproxy also supports HTTP/2 so might be helpful for that as well.<p>We're personally still using HTTP/1.1. But mitmproxy has been a really great tool for us while working on the client and the backend of our project.<p>One thing I also like a lot about mitmproxy is that you can edit requests and replay them. This is useful when I need to step debug the backend for an endpoint where requests are failing or otherwise misbehaving.