Chargebee restricts API requests when you exceed the limits entitled for your plan. The limiting mechanism is employed considering two criteria:
Requests per minute - Number of requests in the past 60 seconds.
Concurrent requests - Number of requests at an instance of time.
When the upper limit is breached on either of the above criteria, an HTTP 429 error response is returned for subsequent requests. As a result, no more requests are served until the limit resets (in approximately a minute).
If you need a temporary increase in the API rate limit, you can contact support@chargbee to avail of it. Further, if you breach the limit frequently, we suggest you move to a higher plan to accommodate the volume of requests