X-Gateway-Cache-Key
The unofficial X-Gateway-Cache-Key response header exposes the exact key a hosting-side gateway cache used to store and look up the response. The header belongs to a four-header family beside X-Gateway-Cache-Status, X-Gateway-Request-ID, and X-Gateway-Skip-Cache, observed on WordPress hosting behind Cloudflare.
Usage
Seeing the cache key spelled out answers cache questions directly: two responses with different keys never share a cache entry, so comparing keys answers why a page misses where a sibling hits. The observed key concatenates six pipe-delimited fields, with three left empty on every crawled response.
Values
The observed format:
<generation>|<tier>|<scheme>|<host>|||<path>
The first field holds a fractional epoch timestamp,
reading as the key generation or cache epoch, with
0 on a share of responses. The second field reads
standard across every observed response, naming a
cache tier or plan of the gateway. Scheme, host, and
path complete the key, while the three empty fields
between host and path leave room for variants the
crawl never observed, matching how cache keys
reserve slots for device class or language variants.
Example
A cache key for a robots.txt fetch over HTTPS. The epoch prefix pins the key to a cache generation, so a platform-wide flush moves the epoch and retires every stored entry at once.
X-Gateway-Cache-Key: 1768208297.312|standard|https|www.example.re|||/robots.txt