Is there a restriction on the number of API calls allowed per day?
We do not have any limit on the number of API calls per day. However, we've set a threshold for individual APIs whereby a user can only make N number of calls in a specified time interval. The supported number of calls and time interval alters based on the API used. Once the user reaches the threshold, the user will be blocked for a specific time interval from using the corresponding API. The thresholds are in place to make sure our APIs are not vulnerable to DDoS attacks.
Here's an example, where a user calls a particular API up to 50 times (defined as "threshold") in a span of 5 minutes (defined as "duration"). On exceeding the above threshold set by Site24x7, the user gets locked out of using the specific API for a specific "lock-period". After serving the lock period, the user will be able to start using the API once again.