[Nodraak]

Would not be able to exactly explain the features and differences, but https://mitmproxy.org/ is a similar project you might be interested in.

[ORioN63]

mitmproxy is indeed a similar project. It offers a dashboard similar to devtools (no modifying in there though).

You can, however, write small python scripts that have read-write access to the http flow (request and response objects).

I guess it's a more low level tool, because it doesn't provide mocking and other helpful tools out of the box.

[chrisweekly]

mitmproxy (/mitmdump) is awesome and powerful, and is ideal for integrating w/ other cli tools (like lnav) in chained scripts written in your language of choice. highly recommended.

[donaldihunter]

Yep, mitmproxy is my go-to tool, but HTTP Mock maybe wins for zero-setup convenience.