@argv_minus_one good question, I kind of think 429 is still better than some generic 503Can I give “Retry-After” with 5xx error codes and will it be understood?Besides:> Note that this specification does not define how the origin server identifies the user, nor how it counts requests. For example, an origin server that is limiting request rates can do so based upon counts of requests on a per-resource basis, across the entire server, or even among a set of servers.