Daily limit of API calls

Is there a restriction on the number of API calls allowed per day?

We do have a restriction on the number of API calls allowed per day. You can make 200 API calls/day for every basic and advanced monitor; 40 API calls/day for every network interface in your license. This is exclusive of the API calls made from the Site24x7 web client and mobile app. For MSP accounts, you can make 100 K calls per customer account. 

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, when 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.