Umami is a small, open-source tool that counts the visits to your website without cookies and without storing who the visitors are. This post explains how it works, what it measures, how to run it, and where its limits are.
When you need to inspect, modify, or replay HTTP(S) traffic, few tools are as powerful and flexible as mitmproxy.
It's open-source, scriptable in Python, and works seamlessly as a man-in-the-middle proxy.
Most projects get a license by copying whatever the last project used. This post explains what the main licenses actually ask of people who use your code, how to choose one with three questions, and what the licenses of your dependencies ask of you.