API calls are subject to the default limit of 15 requests per second and exceeding this limit will result in all endpoints returning an HTTP status code of 429. Limits are per API key. If the limit is exceeded, the API Key will be blocked for the remainder of the sample period. If an API key continually hits the call limit, we reserve the right to permanently block the key and to charge a fee to unblock the key.
To determine the API call amount, we monitor the traffic over a sample period. If the traffic results in a particular API key reaching 80% of the limit (i.e., 12 if the limit is 15) over the sample period, then the responses will start to contain a throttle node which contains useful information on how close you are to reaching the call limit.