Convert OpenAPI 3.0 to Swagger 2.0

Question

Is there a generator to convert OpenAPI 3.0 to Swagger 2.0?

Mashery, an API gateway, requires Swagger 2.0 format on input to open endpoint.

Answer 1

• LucyBot api-spec-converter (online version, GitHub repo, Node.js module) can convert from OpenAPI 3.0 to 2.0.

• API Transformer (paid service) also claims to be able to convert OpenAPI 3.0 back to OpenAPI 2.0. It has a command-line version too.

Keep in mind that OAS3→OAS2 convertion is lossy in general, because OAS3 has features that did not exist in OAS2 (such as multiple servers, oneOf/anyOf, different schemas per media type, objects in query string parameters, cookie parameters, and others).

Answer 2

I needed version 2.0 for Power Automate.

When you are building some Azure Functions, try to create them in Visual Studio and enable any checkbox that is named Swagger not OpenAPI.

Now the API of your Azure Function contains the swagger.json that you can set into Power Automate Custom Connector.

Answer 3

There is also an abandoned GitHub project https://github.com/kongchen/swagger-maven-plugin that is quite useful. We forked this project and adapted it to our needs (we have to use Google Endpoints which requires OAS 2.0)!