[dredmorbius]

There were numerous of these.

Privoxy, dansguardian, Squid (AFAIR), and others.

The notion that SSL/TLS means that ONLY the webserver origin and web browser client are permitted to see or mitigate content ... is itself harmful. Trusted proxies under your control do have a place, though yes, that introduces new points of contention as well.

[captn3m0]

I used to swear by Privoxy till the internet realised HTTPS was actually important and it stopped working everywhere.

[dredmorbius]

Largely the same. Privaxy actually looks pretty sweet in that regard.