Clients send an HTTP/1.1 GET request to /.well-known/webfinger.

Query parameters and the response is defined on an ad-hoc basis. Different kinds of resource queries have their own parameters and responses.

resource is a query parameter for what in particular you want to know about such as a specific account name.

rel is a query parameter for what kind of data records are relevant.

Response format

{
"subject": "a string naming the subject of the query",
"aliases": [
   ... array of strings for names identitcal to the subject ...
],
"properties": {
   "http://example.com/ns/blobcat": "blobcatbongo"
   ...
},
"links": {
   {
      "rel": "relationship to the subject",
      "type": "media type held at href",
      "href": "URI to where to get this data",
      "titles": {
        "en-us": "Tags of language code to translated titles",
        "sv": "Bork bork bork"
      },
      "properties":
         same as properties tag above
         ...
      }
   },
   ...
}

OpenID Connect

Send:

resource=acct:carol@example.com

rel=http://openid.net/specs/connect/1.0/issuer

Receive:

HTTP/1.1 200 OK
Access-Control-Allow-Origin: *
Content-Type: application/jrd+json

{
 "subject" : "acct:carol@example.com",
 "links" :
 [
   {
     "rel" : "http://openid.net/specs/connect/1.0/issuer",
     "href" : "https://openid.example.com"
   }
 ]
}