In IBM API Connect v10.0.3, rate limiting for APIs can be defined in two primary places: Plan and Catalog .

Plan : Rate limiting is typically defined at the Plan level. A Plan in API Connect specifies how an API or a group of APIs is exposed to consumers. It can include rate limits, quotas, and other restrictions. Defining rate limits at the plan level ensures that each application subscribed to the plan adheres to the specified API consumption limits, such as the number of API calls allowed within a given time period.

Catalog : The Catalog is another place where rate limits can be defined. A Catalog represents a collection of APIs and their configurations, including security and rate limiting policies. Rate limits defined at the Catalog level apply globally to all APIs and applications within that Catalog, providing an overarching control mechanism to enforce consumption limits across different APIs.

These two locations allow flexibility in controlling API usage, either by restricting usage per plan (at a more granular level) or globally across all APIs within a catalog.

References:

IBM API Connect v10.0.3 - Now Available

IBM API Connect Documentation