translating webhook ?

A common translation for “hook” in web development is “crochet” (see https://glossaire.traduc.org/ for example) or sometimes “point d’entrée”.

“point d’ancrage” is a mix between the both translations, maybe a pretty good idea.

Depending of the context, we may use English word “hook” which is well-known (and commonly used) by all developers.

“web” should indeed stay “web” in French.