The new output caching middleware in .NET 7 Preview 6 brings a flexible and easy-to-use caching layer to ASP.NET APIs. Setup requires just two extension methods (AddOutputCache and UseOutputCache). By default, caching keys on the full URL including query parameters, but this can be customized using VaryByQuery, VaryByHeader, or VaryByValue. Cache expiration, cache tags for targeted purging, route groups, named policies, and base policies are all supported. The middleware works with both minimal APIs and traditional controllers. Authorized requests are excluded from caching by default, and simultaneous cache-miss requests are coalesced so the handler runs only once.
