The PEDS (Patent Examination Data System) service providers do have a swagger page for thier api but it's using an older verison of the swagger user interface. The biggest difference I see is that curl commands are generated in the new version. Here I've taken the PEDS swagger object and wrapped it in the newer version of swagger ui.
The PEDS swagger object itself is using swagger version 2.0. There is a 3.0 version out now which is also known as the OpenAPI specification. Here is the same updated swagger user interface using the PEDS swagger object which I converted to swagger 3.0/Open Api (using an opensource project). It looks the same as the swagger 2.0 version but there is a subtle difference. Some opensource projects use the swagger 2.0 object as input and some use the swagger 3.0/OpenAPI object. It's more thoroughly explained in this longer article that makes the case for swagger for patentsview, a similar api.
Note that the swagger pages currently do not work from my domain in most browsers. Chrome throws this error:
/swagger/#/home/showHomePageUsingGET:1 Failed to load https://ped.uspto.gov/api/: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://peds.historicip.com' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.