Reference
Response headers
Besides the body, every answer carries a few headers: what the call cost, what is left, what was dropped and how long to wait. Browsers can read them too.
Checked 26 October 2026
The headers
| Header | On | Holds |
|---|---|---|
x-nokeep-credits | Whole replies | What the call cost, in credits. On a stream, read usage.nokeep_credits in the last chunk. |
x-nokeep-balance | Whole replies | The account’s bought credits after the call. |
x-nokeep-ignored | Any call that dropped a field | The fields the model couldn’t take, comma-separated. |
x-ratelimit-limit-requests | Keyed calls | Requests a minute this key may send. |
x-ratelimit-remaining-requests | Keyed calls | Requests left in the current minute. |
retry-after | Every 429 and 503 busy | Seconds to wait before retrying. |
x-nokeep-test | Test-key calls | 1: the reply came from the test key, not a model. |
The API allows calls from any web page, and exposes these headers to them.