A terribly designed API with a complete and orderly OpenAPI 3.0.0 spec will get 5/5. A well designed API with no OpenAPI support or 3.1.x spec support will get a poor design score. I think user generated content might be the way to go for Design. Let people score and review the design quality.
Thanks for your feedback! APIRank is new, and we are here to improve it and make it useful to the community.
APIRank only considers APIs with an OpenAPI or Swagger specification. It supports any version of Swagger v2+ or OpenAPI v3+.
However, I agree in practice for people, the "design criterium" is not only the compliance to the spec ;)
Antoine