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Build an API without a spec

No spec yet? Define resources and fields in the UI and Understudy gives you a working, stateful CRUD API. No OpenAPI file, no code, no YAML.

Sometimes the API you want to stand in for does not exist yet. You are designing it, or building a client against shapes you only have in your head. You do not need a spec to start.

Author it in the UI

  1. Start a blank simulation with "Author manually" on the home screen.
  2. Add resources from the sidebar.
  3. Define fields on each one, using every field type, including references, generated ids, and nested objects and arrays.

The moment you do, you get the same working, stateful CRUD API you would get from an imported spec. POST persists, GET returns it, and update and delete all work.

How it stays honest

Understudy is contract-driven, and manual authoring is no exception. Rather than running a separate mode with different rules, it builds a contract behind the scenes from the resources and fields you define. So everything else, the validation, the response shaping, the export, works exactly as it does for an imported API. One set of rules, however you started.