app.swaggerhub.com
In short: Swagger Studio (app.swaggerhub.com) accepts public api definition catalog. It is free to submit, takes a moderate amount of preparation, and scores 84/100 on our impact ranking (high impact).
Publish a real your tool OpenAPI definition publicly with an accurate description and external documentation URL.
API must be genuine and the spec valid; set visibility to public and publication status accurately, with no credentials in examples.
Priority is high, which sets the band. It is free and moderate to complete, which adjusts it within that band. The score ranks your queue — it is not a measure of domain authority.