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In addition, there is also a special tier called Unlimited, which allows unlimited access. It can be disabled by editing the <TierManagement> node of the api-manager.xml file. For more information on file-based configurations, refer to api-manager.xml configurations.
When creating an API, you can select multiple entries from the list of default tiers. Also, you can add your own tiers to the API Manager using the instructions in section Adding New Throttling Tiers. At subscription time, the consumers of the API can choose which tier they are interested in. Accordingly, the subscriber is granted a maximum number of requests as defined in the tier s/he selected. For information on subscribing to a published API as an API consumer, refer to section Subscribing to APIs.
Throttling can also be set at the application-level using the API Store. You can find more information on Application-Level Throttling.
Go back to to Tier Availability section in Creating an API page.