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 100 requests per minute.
Every call method returns a response header with rate limit status:
X-RateLimit-Limit: 100
X-RateLimit-Remaining: 98
X-RateLimit-Reset: 1580919168
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.