Activity Types Reference

This reference covers all activity types used in ActivityPub federation.

Content Activities

Create

Creates new content:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Create",
  "id": "https://example.com/activities/1",
  "actor": "https://example.com/users/alice",
  "object": {
    "type": "Note",
    "id": "https://example.com/notes/1",
    "content": "Hello, world!"
  },
  "to": ["https://www.w3.org/ns/activitystreams#Public"]
}

Processing: Store the object, notify recipients.

Update

Modifies existing content:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Update",
  "id": "https://example.com/activities/2",
  "actor": "https://example.com/users/alice",
  "object": {
    "type": "Note",
    "id": "https://example.com/notes/1",
    "content": "Hello, world! (edited)",
    "updated": "2024-01-15T11:00:00Z"
  }
}

Processing: Verify actor owns object, update stored content.

Delete

Removes content:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Delete",
  "id": "https://example.com/activities/3",
  "actor": "https://example.com/users/alice",
  "object": "https://example.com/notes/1"
}

Processing: Verify ownership, replace with Tombstone.

Social Activities

Follow

Request to follow an actor:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Follow",
  "id": "https://example.com/activities/4",
  "actor": "https://example.com/users/alice",
  "object": "https://other.example/users/bob"
}

Processing: Add to pending follows, send Accept or Reject.

Accept

Accepts a request (usually Follow):

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Accept",
  "id": "https://other.example/activities/5",
  "actor": "https://other.example/users/bob",
  "object": {
    "type": "Follow",
    "id": "https://example.com/activities/4",
    "actor": "https://example.com/users/alice",
    "object": "https://other.example/users/bob"
  }
}

Processing: Add to following list, start receiving content.

Reject

Rejects a request:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Reject",
  "id": "https://other.example/activities/6",
  "actor": "https://other.example/users/bob",
  "object": {
    "type": "Follow",
    "id": "https://example.com/activities/4"
  }
}

Processing: Remove from pending follows.

Reaction Activities

Like

Express appreciation:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Like",
  "id": "https://example.com/activities/7",
  "actor": "https://example.com/users/alice",
  "object": "https://other.example/notes/1"
}

Processing: Store like, notify author.

Announce

Share/boost content:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Announce",
  "id": "https://example.com/activities/8",
  "actor": "https://example.com/users/alice",
  "object": "https://other.example/notes/1",
  "to": ["https://www.w3.org/ns/activitystreams#Public"],
  "cc": [
    "https://other.example/users/bob",
    "https://example.com/users/alice/followers"
  ]
}

Processing: Store boost, notify author, deliver to followers.

Negative Activities

Block

Block an actor:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Block",
  "id": "https://example.com/activities/9",
  "actor": "https://example.com/users/alice",
  "object": "https://other.example/users/spammer"
}

Note: Usually kept local, only federated if you want the blocked party to know.

Flag

Report content/actors:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Flag",
  "id": "https://example.com/activities/10",
  "actor": "https://example.com/users/alice",
  "object": [
    "https://other.example/users/abuser",
    "https://other.example/notes/offensive"
  ],
  "content": "This user is posting abusive content"
}

Processing: Create moderation report for admins.

Undo Activity

Reverses a previous activity:

Undo Follow

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Undo",
  "id": "https://example.com/activities/11",
  "actor": "https://example.com/users/alice",
  "object": {
    "type": "Follow",
    "id": "https://example.com/activities/4",
    "actor": "https://example.com/users/alice",
    "object": "https://other.example/users/bob"
  }
}

Undo Like

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Undo",
  "id": "https://example.com/activities/12",
  "actor": "https://example.com/users/alice",
  "object": {
    "type": "Like",
    "id": "https://example.com/activities/7"
  }
}

Undo Announce

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Undo",
  "id": "https://example.com/activities/13",
  "actor": "https://example.com/users/alice",
  "object": {
    "type": "Announce",
    "id": "https://example.com/activities/8"
  }
}

Collection Activities

Add

Add to a collection (e.g., pin a post):

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Add",
  "id": "https://example.com/activities/14",
  "actor": "https://example.com/users/alice",
  "object": "https://example.com/notes/1",
  "target": "https://example.com/users/alice/collections/featured"
}

Remove

Remove from a collection:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Remove",
  "id": "https://example.com/activities/15",
  "actor": "https://example.com/users/alice",
  "object": "https://example.com/notes/1",
  "target": "https://example.com/users/alice/collections/featured"
}

Migration Activity

Move

Account migration:

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Move",
  "id": "https://old.example/activities/16",
  "actor": "https://old.example/users/alice",
  "object": "https://old.example/users/alice",
  "target": "https://new.example/users/alice"
}

Activity Summary

Activity	Purpose	Common Use
Create	New content	Posts, notes
Update	Edit content	Editing posts
Delete	Remove content	Deleting posts
Follow	Subscribe	Following users
Accept	Approve request	Accept follows
Reject	Deny request	Reject follows
Like	React positively	Favorites
Announce	Share content	Boosts/reblogs
Undo	Reverse action	Unfollow, unlike
Block	Block actor	Blocking users
Flag	Report	Reporting abuse
Add	Add to collection	Pin posts
Remove	Remove from collection	Unpin posts
Move	Migrate account	Account moves

See Also

• Object Types - Content types
• Handling Activities - Processing
• Sending Activities - Delivery