Gloop REST API editor, Preview tab
The Preview tab lets you see what the resulting Swagger, OpenAPI, and Postman files will look like (in JSON and YAML for Swagger and OpenAPI, too). You can use the select box on the right-hand side of the address bar to choose which version you want to preview.
Preview your API in Martini's API Explorer while you edit!
While you're editing a Gloop REST API, you can click on the API Explorer button in the Operations tab to watch your Swagger definition come to life in the API Explorer as you edit it! Every time you save the API, Martini Desktop will reload the specification into API Explorer for you.