ETag headers

[ataylorme]

The ETag header is " an identifier for a specific version of a resource. It allows caches to be more efficient, and saves bandwidth, as a web server does not need to send a full response if the content has not changed."

Pantheon supports Etag headers but WordPress does not add them by default. Advanced Page Cache could improve caching of WordPress sites on Pantheon by adding proper ETag headers.

[danielbachhuber]

For normal pages, this isn't easily possible because WordPress doesn't know what data is present on the page.

In the REST API context, this should be possible.

[ataylorme]

It probably makes sense to use ETag headers on cached REST API responses