What is OpenAPI?
Updated May 2026
OpenAPI is the standard format for describing what an API does, so any tool (or AI) can read it and know how to make calls.
An OpenAPI document is a JSON or YAML file that lists every endpoint, parameter, response shape, and authentication method an API supports. AI tools like ChatGPT custom GPTs use OpenAPI documents to learn how to call an API.
Every withlove agent ships an OpenAPI 3.1 document at /<slug>/openapi.json so any AI tool can read it and call the agent's tools directly.
Frequently asked questions
Is OpenAPI the same as Swagger?
Swagger is the older name. OpenAPI 3.0+ is the current standard, maintained by the OpenAPI Initiative.
Related terms
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