Fern has a first-class integration with Express. Fern automatically generates:

  • Typescript interfaces for your API types
  • Exceptions that you can throw for non-200 responses
  • Interfaces for you to define your business logic.

All the networking/HTTP logic is auto-generated by Fern under the hood.

The Fern Express Starter is a simple example of a Fern-powered Express server.

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Demo video

FastAPIFern Definition