Comment by tshaddox

What are you referring to with the origin needing to support HEAD requests? For HTTP conditional requests your origin just needs to support GET with if-none-match or if-modified-since. Then it responds with a 304 with no body if the cached version is still valid. The origin should, of course, be able to determine cache validity much more cheaply than rendering the whole page, which is usually as simple as checking a single timestamp in the database.

And, of course, you can still use cache-control to permit some duration of staleness, so that you don’t literally revalidate on every request.