Object Types

ActivityStreams defines various object types for representing content. These types describe what kind of content an object represents.

Content Types

Note

Short-form content, similar to a tweet or status update.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Note",
  "id": "https://example.com/notes/1",
  "attributedTo": "https://example.com/users/alice",
  "content": "<p>Hello, world!</p>",
  "published": "2024-01-15T10:00:00Z",
  "to": ["https://www.w3.org/ns/activitystreams#Public"]
}

Used by: Mastodon (toots), Pleroma, Misskey

Article

Long-form content like blog posts.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Article",
  "id": "https://example.com/articles/1",
  "name": "Getting Started with ActivityPub",
  "attributedTo": "https://example.com/users/alice",
  "content": "<p>ActivityPub is a protocol for decentralized social networking...</p>",
  "published": "2024-01-15T10:00:00Z",
  "url": "https://example.com/blog/getting-started"
}

Used by: WriteFreely, Plume, WordPress (with plugin)

Page

A document or web page, often with a title and external URL.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Page",
  "id": "https://lemmy.example/post/12345",
  "name": "Interesting Article About Programming",
  "url": "https://external-site.com/article",
  "content": "<p>Discussion about the article...</p>",
  "attributedTo": "https://lemmy.example/u/alice"
}

Used by: Lemmy (for posts with titles/links)

Event

A scheduled event or activity.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Event",
  "id": "https://example.com/events/1",
  "name": "Fediverse Developer Meetup",
  "startTime": "2024-02-01T18:00:00Z",
  "endTime": "2024-02-01T21:00:00Z",
  "location": {
    "type": "Place",
    "name": "Tech Hub",
    "address": "123 Main Street"
  },
  "attributedTo": "https://example.com/users/alice"
}

Used by: Mobilizon, Gancio

Media Types

Image

A static image.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Image",
  "id": "https://example.com/images/1",
  "name": "Sunset over the ocean",
  "url": "https://example.com/media/sunset.jpg",
  "mediaType": "image/jpeg",
  "width": 1920,
  "height": 1080
}

Video

A video file.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Video",
  "id": "https://peertube.example/videos/1",
  "name": "My First Video",
  "url": [
    {
      "type": "Link",
      "href": "https://peertube.example/videos/1.mp4",
      "mediaType": "video/mp4",
      "height": 1080
    }
  ],
  "duration": "PT5M30S",
  "attributedTo": "https://peertube.example/accounts/alice"
}

Used by: PeerTube

Audio

An audio file.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Audio",
  "id": "https://funkwhale.example/tracks/1",
  "name": "My Song",
  "url": {
    "type": "Link",
    "href": "https://funkwhale.example/audio/song.mp3",
    "mediaType": "audio/mpeg"
  },
  "duration": "PT3M45S",
  "attributedTo": "https://funkwhale.example/users/alice"
}

Used by: Funkwhale

Document

A generic document attachment.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Document",
  "mediaType": "image/jpeg",
  "url": "https://example.com/media/photo.jpg",
  "name": "Photo description for accessibility",
  "blurhash": "LEHV6nWB2yk8pyo0adR*.7kCMdnj",
  "width": 1920,
  "height": 1080
}

Used by: Mastodon (for attachments)

Location Types

Place

A physical location.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Place",
  "name": "San Francisco",
  "latitude": 37.7749,
  "longitude": -122.4194,
  "address": "San Francisco, CA, USA"
}

Properties

Property	Type	Description
`name`	String	Place name
`latitude`	Number	Latitude coordinate
`longitude`	Number	Longitude coordinate
`altitude`	Number	Altitude in meters
`accuracy`	Number	Accuracy in meters
`radius`	Number	Radius in meters
`units`	String	Unit of measurement

Special Types

Tombstone

Represents a deleted object.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Tombstone",
  "id": "https://example.com/notes/1",
  "formerType": "Note",
  "deleted": "2024-01-15T14:00:00Z"
}

Used when: An object has been deleted but needs to return something.

Profile

Describes an actor's profile.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Profile",
  "describes": "https://example.com/users/alice",
  "summary": "Software developer and fediverse enthusiast"
}

Relationship

Describes a relationship between two actors.

{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Relationship",
  "subject": "https://example.com/users/alice",
  "relationship": "http://purl.org/vocab/relationship/friendOf",
  "object": "https://example.com/users/bob"
}

Tag Types

Mention

References another actor.

{
  "type": "Mention",
  "href": "https://example.com/users/bob",
  "name": "@bob@example.com"
}

Hashtag

A topic tag.

{
  "type": "Hashtag",
  "href": "https://example.com/tags/fediverse",
  "name": "#fediverse"
}

Emoji

A custom emoji.

{
  "type": "Emoji",
  "id": "https://example.com/emoji/blobcat",
  "name": ":blobcat:",
  "icon": {
    "type": "Image",
    "mediaType": "image/png",
    "url": "https://example.com/emoji/blobcat.png"
  }
}

Attachment Examples

Note with Image

{
  "type": "Note",
  "content": "<p>Check out this photo!</p>",
  "attachment": [
    {
      "type": "Document",
      "mediaType": "image/jpeg",
      "url": "https://example.com/media/photo.jpg",
      "name": "A beautiful landscape"
    }
  ]
}

Note with Multiple Attachments

{
  "type": "Note",
  "content": "<p>Photo album from my trip</p>",
  "attachment": [
    {
      "type": "Document",
      "mediaType": "image/jpeg",
      "url": "https://example.com/media/photo1.jpg",
      "name": "Beach sunset"
    },
    {
      "type": "Document",
      "mediaType": "image/jpeg",
      "url": "https://example.com/media/photo2.jpg",
      "name": "Mountain view"
    }
  ]
}

Object Type Quick Reference

Type	Description	Example Use
Note	Short text	Toots, posts
Article	Long text	Blog posts
Page	Web page	Link posts
Event	Scheduled event	Meetups
Image	Picture	Photo posts
Video	Video content	Video hosting
Audio	Audio content	Music, podcasts
Document	Generic file	Attachments
Place	Location	Check-ins
Tombstone	Deleted content	Deletion markers
Mention	User reference	@mentions
Hashtag	Topic tag	#hashtags
Emoji	Custom emoji	:emoji:

Content Representation

HTML Content

Most implementations expect HTML in the content property:

{
  "type": "Note",
  "content": "<p>Hello <a href=\"https://example.com/@bob\">@bob</a>!</p>",
  "mediaType": "text/html"
}

Plain Text

For plain text, use mediaType:

{
  "type": "Note",
  "content": "Hello @bob!",
  "mediaType": "text/plain"
}

Source

Preserve the original source format:

{
  "type": "Note",
  "content": "<p>Hello <strong>world</strong>!</p>",
  "source": {
    "content": "Hello **world**!",
    "mediaType": "text/markdown"
  }
}

Next Steps

Actor Types - Actor types
Properties - All properties
Link Types - Link types

Content Types​

Note​

Article​

Page​

Event​

Media Types​

Image​

Video​

Audio​

Document​

Location Types​

Place​

Properties​

Special Types​

Tombstone​

Profile​

Relationship​

Tag Types​

Mention​

Hashtag​

Emoji​

Attachment Examples​

Note with Image​

Note with Multiple Attachments​

Object Type Quick Reference​

Content Representation​

HTML Content​

Plain Text​

Source​

Next Steps​