Verified against AS2 Core & Vocabulary (W3C REC 2017), the published AS2 JSON-LD context, ActivityPub REC, Mastodon v4.7.3 source (context_helper.rb, account.rb, json_ld_helper.rb), Lemmy 0.19.20 page.rs, Mastodon status_parser.rb, WordPress ActivityPub FEDERATION.md, Mobilizon/Gancio/Funkwhale sources and docs on 2026-10-15.

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, Ghost, the WordPress ActivityPub plugin (Article for standard posts, Note otherwise — FEDERATION.md). Mastodon shows Articles as title, summary and link rather than full content — see Big Platforms.

Page

A web page or document (it extends Document in the AS2 Vocabulary).

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

Used by: Lemmy, for community posts. Lemmy puts a link post's external URL in attachment as a Link, not in url (its 0.19 Page struct has no url field — page.rs). See Lemmy Compatibility.

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"
  },
  "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, which sends media attachments as Document. blurhash is a Mastodon extension (toot:blurhash), not AS2, and needs its context mapping.

Location Types

Place

A physical location.

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

Properties

Property	Type	Description
`name`	String	Place name
`latitude`	Number	Latitude coordinate
`longitude`	Number	Longitude coordinate
`altitude`	Number	Altitude, in `units` (default metres)
`accuracy`	Number	Accuracy as a percentage, 0–100 (e.g. `94.0` = 94% accurate)
`radius`	Number	Radius around the point, in `units` (default metres)
`units`	String	`cm`, `feet`, `inches`, `km`, `m`, `miles`, or a URI

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.

:::note Not part of core AS2 Hashtag and Emoji are fediverse extensions, not ActivityStreams 2.0 types (AS2 only defines Mention as a Link subtype). Include their context mappings, e.g. "Hashtag": "as:Hashtag" and Mastodon's "Emoji": "toot:Emoji". :::

{
  "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 (extension)	Topic tag	#hashtags
Emoji (extension)	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

AS2 lets you mark plain text with mediaType (the default is text/html). Mastodon ignores mediaType here and treats content as HTML, sanitising it (status_parser.rb), so line breaks in plain text are lost — send HTML if Mastodon users are your audience:

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

Source

Preserve the original source format with ActivityPub's source property (AP §3.3), which clients use to re-edit content:

{
  "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​