All the calls to the API methods are limited globally to a certain number of request per minute.
This limit is set by account, that means that all the calls using any of the API Keys of the same account count to reach this global limit, which is currently set to 10 requests per second.
If you make a call to the API and the Rate Limit has been reached, it will response with a "429 Too Many Requests" HTTP status.
Every call method returns a response header with rate limit status:
RateLimit-Policy: 10;w=1
RateLimit-Limit: 10
RateLimit-Remaining: 9
RateLimit-Reset: 1
RateLimit-Reset header tells you how many seconds remain until your rate limit window resets.
Retry-After: 1
This standard header is present only when the limit has been reached. It indicates how many seconds you should wait before making a follow-up request (see Retry-After).
X-RateLimit-Limit: 10
X-RateLimit-Remaining: 9
X-RateLimit-Reset: 1580919168
X-RateLimit-Reset indicates the time when the current rate limit window will reset. The value expressed is a Unix timestamp, representing the number of seconds since January 1, 1970 (UTC). In the above example 1580919168 corresponds to 2020-02-05T14:32:48Z (UTC).