420
HTTP 420 · Enhance Your Calm
HTTP status 420 "Enhance Your Calm", the unofficial code Twitter's API sent back when an app was asking too fast (rate limited). Printed in Twitter's response-codes table and still printed in X developer docs.
When a computer asks a website for something, the website answers with a three-digit number. 200 means OK. 404 means not found. When an app asked Twitter too many questions too fast, Twitter answered 420 and gave it a name: "Enhance Your Calm". In plain words: slow down. It was never part of the official web standard. The official slow-down code, 429 Too Many Requests, only came in 2012. X's developer docs still print the line: "420 Enhance Your Calm: Rate limited; wait and retry."
What it supports
A real, documented wire code with its own name, printed by the company that used it. Twitter's response-codes table lists "420 | Enhance Your Calm | Returned when an app is being rate limited for making too many requests", next to "429 | Too Many Requests". The public list of HTTP codes records it as an unofficial code from version 1 of the Twitter Search and Trends API; versions 1.1 and later use 429. The IANA HTTP status-code registry has no 420 at all, so this number is Twitter's own choice, not a seat in the official table. RFC 6585 (April 2012) is what added 429. Twitter $54.20 is another 420 in Twitter's story. Same family, different object.
What it does not
Not a reason for the choice; no primary says why Twitter picked 420 or the phrase, so we do not say. Not an official web standard (that is 429). Not what every X endpoint sends today. Not linked to the $54.20 bid or the 4/20 check date. Not 42. Not Adams.
ExactnessDesignation
Form420
UnitHTTP status code
Strengthattested
Hung31 October 2026