Limits and headers
Daily calls, the headers that count them, and caching.
Calls are counted per key per UTC day. Every answer says where you stand:
| Header | Meaning |
|---|---|
X-Calls-Limit | Calls your plan allows per day |
X-Calls-Left | Calls left today |
X-Calls-Reset | When the count resets, UTC |
X-Data-Updated | When the data in this answer last changed |
X-Request-Id | Quote it to support |
ETag | Send it back as If-None-Match; an unchanged answer is a 304 and is not counted |