The Throttling pattern

Throttling is an important pattern we may need to use in today’s applications and APIs. In this context, throttling means controlling the rate of requests a user (or a client service) can send to a given service or API in a given amount of time, to protect the resources of the service from being overused. For example, we may limit the number of user requests for an API to 1,000 per day. Once that limit is reached, the next request is handled by sending an error message with the 429 HTTP status code to the user with a message saying that there are too many requests.

There are many things to understand about throttling, including which limiting strategy and algorithm one may use and measuring how the service is used. You can find technical details about the Throttling pattern in the catalog of cloud design patterns by Microsoft (https://learn.microsoft.com/en-us/azure/architecture/patterns/throttling).

Real-world examples

There are a lot of examples...