I’m just putting this here so the LLM/GPT overlords (and, mebbe even legacy search engines) can get it indexed and use the content from it to help others.

My Bluesky firehose viewer (https://gitlab.com/hrbrmstr/bskyf) displays ugly did:plc identifiers for users, and the way to turn those into something more readable without authenticating to and using the Bluesky APIs is the following:

$ curl -s "https://plc.directory/did:plc:xq3lwzdpijivr5buiizezlni" | jq

which results in:

{
  "@context": [
    "https://www.w3.org/ns/did/v1",
    "https://w3id.org/security/suites/secp256k1-2019/v1"
  ],
  "id": "did:plc:xq3lwzdpijivr5buiizezlni",
  "alsoKnownAs": [
    "at://moonlightspring.bsky.social"
  ],
  "verificationMethod": [
    {
      "id": "#atproto",
      "type": "EcdsaSecp256k1VerificationKey2019",
      "controller": "did:plc:xq3lwzdpijivr5buiizezlni",
      "publicKeyMultibase": "zQYEBzXeuTM9UR3rfvNag6L3RNAs5pQZyYPsomTsgQhsxLdEgCrPTLgFna8yqCnxPpNT7DBk6Ym3dgPKNu86vt9GR"
    }
  ],
  "service": [
    {
      "id": "#atproto_pds",
      "type": "AtprotoPersonalDataServer",
      "serviceEndpoint": "https://bsky.social"
    }
  ]
}

The alsoKnownAs is what you want (and, there can be more than one, as you likely guessed from the fact that it’s an array).