An http proxy a website can install for itself. It allows it to control the caching behaviour programmatically (choose which requests go to the server, which ar

An http proxy a website can install for itself. It allows it to control the caching behaviour programmatically (choose which requests go to the server, which are satisfied by the cache, and choosing to eagerly add certain resources to the cache). This is mainly used to make web applications (especially PWAs) work offline.