Visual editing of an API definition

Greetings!  I'm a relatively new Open API user, and while I just love writing raw YAML in my favorite text editor of choice (vim or Sublime), I feel it would sometimes be easier if one could get started in a truly visual environment.

I saw on the SwaggerHub website that "SwaggerHub provides Visual Editor for OpenAPI 2.0 and OpenAPI 3.0 definitions so that you can update your API information without having to understand the YAML syntax." This is *just* what I'm looking for!  But... aye, there's the rub: [it's only] Available in SwaggerHub SaaS, SwaggerHub On-Premise 1.20.0 and later.

I am absolutely not in a situation to set up my own on-premise SwaggerHub installation.

So... anybody got any suggestions as an alternative to the SwaggerHub Visual Editor?

Help much appreciated,

Garry Offord