One thing I keep coming back to when comparing #ActivityPub and AT Protocol: ActivityPub is basically a convention on top of the #web stuff we already have. An actor is a JSON-LD document you GET. An inbox is an endpoint you POST to. If you already run a website, you can bolt this on without changing the site's basic shape. Ghost didn't set out to join the #fediverse, and then years later it could, just by adding an endpoint.
AT Protocol feels less like that to me. Running a PDS means a signed repo, a Merkle search tree, a firehose, a DID. It's not a layer you add to an existing site. It's closer to standing up another backend beside it.
I think that's why ActivityPub keeps making sense to me. You can join later. You don't have to have built the whole thing with federation in mind from day one.
#ATProto #ATProtocol #fedidev
洪 民憙 (Hong Minhee) :nonbinary:
npub1pz…r3zhj
2026-07-09 04:07:00 UTC
Author Public Key
npub1pzjfm9lymy3dnrxg2uk237vlvteefahea7s4ptjzv8n2a9uarrxqtr3zhjSeen on
wss://relay.mostr.pubPublished at
2026-07-09 04:07:00 UTCEvent JSON
{
"id": "51ee0f03198bce536bcd5d344f8cd319382b53efb7e9be669f1c631324cbe1c1",
"pubkey": "08a49d97e4d922d98cc8572ca8f99f62f394f6f9efa150ae4261e6ae979d18cc",
"created_at": 1783570020,
"kind": 1,
"tags": [
[
"t",
"web"
],
[
"t",
"atproto"
],
[
"t",
"fedidev"
],
[
"t",
"fediverse"
],
[
"t",
"atprotocol"
],
[
"t",
"activitypub"
],
[
"proxy",
"https://hollo.social/@hongminhee/019f450e-b5cd-73e2-8055-2c792a7d6c86",
"activitypub"
],
[
"client",
"Mostr",
"31990:6be38f8c63df7dbf84db7ec4a6e6fbbd8d19dca3b980efad18585c46f04b26f9:mostr",
"wss://relay.ditto.pub"
]
],
"content": "One thing I keep coming back to when comparing #ActivityPub and AT Protocol: ActivityPub is basically a convention on top of the #web stuff we already have. An actor is a JSON-LD document you GET. An inbox is an endpoint you POST to. If you already run a website, you can bolt this on without changing the site's basic shape. Ghost didn't set out to join the #fediverse, and then years later it could, just by adding an endpoint.\n\nAT Protocol feels less like that to me. Running a PDS means a signed repo, a Merkle search tree, a firehose, a DID. It's not a layer you add to an existing site. It's closer to standing up another backend beside it.\n\nI think that's why ActivityPub keeps making sense to me. You can join later. You don't have to have built the whole thing with federation in mind from day one.\n\n#ATProto #ATProtocol #fedidev\n",
"sig": "af26a8231bb5e5ef35041a33a95bc70baad63f367ccd50e13af4cd0741cf5951d13cc2fcb5ea74acee6dc1eaa011426735e22cdafdd3978693185143dee7c18b"
}