How is this different from writing OpenAPI by hand?
Writing an OpenAPI document by hand means learning the format before you can describe the API you already have in your head. This goes the other way round: describe what the API should do in a sentence or two, and get back a complete specification you can read, edit and download. The result is shown in an editor so you can check it rather than trust it, and you can ask for changes — adding authentication and pagination, or regenerating a different design — without starting again.
What does this tool give you?
Describe your API in plain English and get an AI-generated starter OpenAPI spec, with 3 free AI prompts to iterate on it.
What do Postman Agent Mode and Spec Hub give you?
Agent Mode helps create and refine OpenAPI, AsyncAPI, GraphQL, Proto, and Smithy specifications in Spec Hub’s visual and code editors. You can generate Collections with two-way sync, collaborate with Git-backed version history, lint specifications in CI on any plan, and define custom governance rulesets on Enterprise. AI credits vary by plan.
How do I create an OpenAPI spec without writing YAML by hand?
Describe the API in plain English and the AI-generated starter spec gives you a working OpenAPI draft to refine, rather than writing YAML from scratch.
Can I generate specs in AsyncAPI, GraphQL, or Proto too, not just OpenAPI?
Yes — Agent Mode creates specs in OpenAPI, AsyncAPI, GraphQL, Proto, or Smithy, not just OpenAPI.
Is there a free way to generate an OpenAPI spec online?
Yes — this tool gives 3 free AI prompts to generate and iterate on a starter spec with no signup.