[twiss]

Possibly https://github.com/freedomofpress/webcat? (I also made one, a long time ago: https://github.com/twiss/hcs-checker-firefox.)

There is also an effort to build this into browsers directly, which we (Proton) are involved with:

https://github.com/twiss/source-code-transparency (old initial proposal)

https://github.com/beurdouche/explainers/blob/main/waict-exp... (more recent proposal)

https://github.com/beurdouche/w3c-waict/blob/main/waict.bs (very early draft specification)