REST APIs created via Gloop REST API Editor automatically generates a Swagger (OpenAPI and Postman Collection as well) compliant format that is readily available for you to copy and save to a file. If you don't have an existing API, you can create a new Gloop REST API and publish your existing Gloop Services as REST API operations.
Creating a file directly isn't supported but as I mentioned earlier, you can copy any of the formats to a file and save it in a format you desire. The Gloop REST API Editor also provides a preview link that allows you to also access an API format you fancy, from there you can download the Swagger/OpenAPI version of your API from Martini.
The following formats are supported by Gloop REST API Editor:
Creating a swagger file
Creating a swagger file
I'd like to create a swagger file. I don't have an existing api. Any suggestions?