API Umbrella

Acts as a proxy layer above existing APIs, allowing features like access control and rate limiting to be added without modifying API code, as stated in the README: 'API Umbrella acts as a layer above your APIs, so your API code doesn't need to be modified.'

Presents disparate APIs running on different servers or written in different languages as a single cohesive endpoint, improving consumer experience, per the README: 'Present separate APIs as a cohesive offering... exposed at a single endpoint.'

Provides standardized API key credentials, rate limiting, and usage analytics out of the box, handling common infrastructure concerns centrally without backend changes.

Offered under the MIT license, it allows full customization and self-hosting, avoiding vendor lock-in and reducing costs compared to commercial solutions like Apigee.