Most of the good stuff here (using the full range of HTTP verbs and status codes, idempotent GET, stable URLs) is already common knowledge among web developers

Most of the good stuff here (using the full range of HTTP verbs and status codes, idempotent GET, stable URLs) is already common knowledge among web developers and built into any modern framework. URNs are interesting but difficult to work with in practice; 402 Payment Required has been "reserved for future use" forever. Then there's the suggestion to use custom HTTP methods, which is ill-advised [1]. [1]: http://programmers.stackexchange.com/a/193826 http://programmers.stackexchange.com/a/193826