Hello,
I would like to know each limits of the APIs. and also is there any limits of the Apps? or is the limits only for the users?
What limits are you asking about specifically?
For API rate limits we don't publish the explicit limits, but there are things you should be mindful of when interacting with the API. You can read about how to handle these limits in our Performance guide, and our Error Handling guide.
For app limits there is a maximum number of users that can be connected before your app is frozen and you need to apply for production. You can learn about that process here, under 'Production approval'.
