HTTP status codes used by world-famous APIs

statuses.md

API	Status Codes
Twitter	200, 304, 400, 401, 403, 404, 406, 410, 420, 422, 429, 500, 502, 503, 504
Stripe	200, 400, 401, 402, 404, 429, 500, 502, 503, 504
Github	200, 400, 422, 301, 302, 304, 307, 401, 403
Pagerduty	200, 201, 204, 400, 401, 403, 404, 408, 500
NewRelic Plugins	200, 400, 403, 404, 405, 413, 500, 502, 503, 503
Etsy	200, 201, 400, 403, 404, 500, 503
Dropbox	200, 400, 401, 403, 404, 405, 429, 503, 507
Spotify	200, 201, 204, 304, 400, 401, 403, 404, 429, 500, 502, 503
Google Cloud	200, 301, 304, 307, 308, 400, 401, 403, 404, 405, 409, 411, 412, 416, 429, 500, 501, 503
HipChat	200, 201, 202, 400, 401, 403, 404, 405, 429, 500, 503
Telegram	200, 303, 400, 401, 403, 404, 420, 500
Pocket	200, 400, 401, 403, 503
Uber	200, 201, 400, 401, 403, 404, 406, 409, 422, 429, 500

Used by either one of them: 200, 201, 202, 204, 301, 302, 303, 304, 307, 308, 400, 401, 402, 403, 404, 405, 406, 408, 409, 410, 411, 412, 413, 416, 420, 422, 429, 500, 501, 502, 503, 504, 507

Used by at least two of them: 200, 201, 204, 301, 304, 307, 400, 401, 403, 404, 405, 406, 409, 420, 422, 429, 500, 502, 503, 504

Used by at least three of them: 200, 201, 304, 400, 401, 403, 404, 405, 422, 429, 500, 502, 503

Used by at least four of them: 200, 201, 304, 400, 401, 403, 404, 405, 429, 500, 502, 503

Used by at least five of them: 200, 201, 400, 401, 403, 404, 405, 429, 500, 503

Used by all of them: 200, 400

GitHub returns 404 in at least some cases.

Modern status codes for Google Cloud: 200, 400, 401, 403, 404, 409, 429, 499, 500, 501, 503, 504
Source: https://github.com/googleapis/googleapis/blob/master/google/rpc/code.proto