ActivityPub Federation

JSS includes a built-in ActivityPub server, allowing your Solid pod to federate with Mastodon, Pleroma, Misskey, and any ActivityPub-compatible service.

Quick Start

jss start --activitypub --ap-username alice --ap-display-name "Alice"

Your actor is now discoverable at @alice@yourserver.com from any Mastodon instance.

Configuration

Flag	Description	Default
--activitypub	Enable ActivityPub	Off
--ap-username <name>	Actor username	me
--ap-display-name <name>	Display name	Username
--ap-summary <text>	Bio / summary	Empty
--ap-nostr-pubkey <hex>	Link Nostr identity via alsoKnownAs	None

Endpoints

Endpoint	Method	Description
/.well-known/webfinger	GET	Actor discovery
/.well-known/nodeinfo	GET	Server metadata (Mastodon-compatible)
/profile/card	GET	Actor profile (content-negotiated)
/inbox	POST	Receive activities from remote servers
/profile/card/outbox	GET	Published activities (last 20)
/profile/card/outbox	POST	Create and broadcast new posts
/profile/card/followers	GET	Followers collection
/profile/card/following	GET	Following collection

Supported Activities

Incoming (Inbox)

Activity	Behavior
Follow	Adds follower, auto-sends Accept
Undo	Removes follower
Accept	Marks outgoing follow as accepted
Create	Stores received note/post
Like	Stores like activity
Announce	Stores boost/reblog

Outgoing (Outbox)

Post a note:

curl -X POST https://yourserver.com/profile/card/outbox \
  -H "Content-Type: application/activity+json" \
  -d '{"type": "Note", "content": "Hello from my Solid pod!"}'

JSS wraps it in a Create activity, signs it with HTTP Signatures, and delivers to all follower inboxes.

Security

• HTTP Signature verification: Validates signatures on incoming activities using the remote actor's public key
• Actor caching: Caches remote actor profiles to reduce network requests
• RSA keypair: Generated automatically and stored in .server/ directory
• Activity validation: Requires valid type field on all incoming activities

Nostr Identity Linking

Link your Nostr identity to your ActivityPub actor:

jss start --activitypub --ap-nostr-pubkey <hex-pubkey>

This adds an alsoKnownAs reference to your actor profile, enabling cross-protocol identity verification.

NodeInfo

JSS exposes NodeInfo 2.1 metadata at /.well-known/nodeinfo, compatible with Mastodon and other Fediverse tools that discover server capabilities.