Hi Geert, I'm the author of Betamax. While its primary use is for testing (and it has integrations with different testing utilities to help with testing projects) people have and do use it in other contexts (although they're in the minority).
That said, Betamax does not behave like a proxy would in the way it captures HTTP interactions. Perhaps my description of my own package needs improvement. Betamax specifically will (when explicitly instructed to do so) record HTTP interactions when using python-requests. A slightly more generic, but equally explicit, package to record any HTTP interaction using Python is VCRpy. To record *any* HTTP interaction on a system, you'll have better luck with a proxy like mitmproxy. That can intercept, record, and reply any HTTP interaction on your system. Cheers, Ian