I need to integrate graph APi to fetch calendar events, is it free at the time of development?

Question

Please tell me is there any charges at the time of development, and in the time of production use.

Answer 1

No, the Graph API is free of charge. There are few exceptions, but Calendaring isn't one of them. The documentation explicitly mentions such requirements for each of the relevant endpoints, so make sure to consult it as you develop your app.