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Properties Reference

This is a comprehensive reference of all properties defined in ActivityStreams 2.0.

Core Properties​

@context​

JSON-LD context definition.

{
  "@context": "https://www.w3.org/ns/activitystreams"
}

Can be an array for multiple contexts:

{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    "https://w3id.org/security/v1",
    {
      "toot": "http://joinmastodon.org/ns#",
      "sensitive": "as:sensitive"
    }
  ]
}

type​

The object type(s).

{ "type": "Note" }
{ "type": ["Note", "Object"] }

id​

Globally unique identifier (URI).

{ "id": "https://example.com/notes/12345" }

Object Properties​

name​

Human-readable name/title.

{ "name": "My Blog Post" }

nameMap​

Localized names.

{
  "nameMap": {
    "en": "Hello",
    "de": "Hallo",
    "ja": "こんにちは"
  }
}

content​

Text content (typically HTML).

{ "content": "<p>Hello, world!</p>" }

contentMap​

Localized content.

{
  "contentMap": {
    "en": "<p>Hello, world!</p>",
    "es": "<p>¡Hola, mundo!</p>"
  }
}

summary​

Brief description or content warning.

{ "summary": "Discussion of spoilers" }

mediaType​

MIME type of content.

{ "mediaType": "text/html" }
{ "mediaType": "text/markdown" }

source​

Original source format.

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

Temporal Properties​

published​

When the object was created.

{ "published": "2024-01-15T10:30:00Z" }

updated​

When the object was last modified.

{ "updated": "2024-01-15T14:45:00Z" }

startTime​

Start time for events or activities.

{ "startTime": "2024-02-01T18:00:00Z" }

endTime​

End time for events.

{ "endTime": "2024-02-01T21:00:00Z" }

duration​

Duration in ISO 8601 format.

{ "duration": "PT2H30M" }

Attribution Properties​

attributedTo​

Who created the object.

{ "attributedTo": "https://example.com/users/alice" }

Multiple authors:

{
  "attributedTo": [
    "https://example.com/users/alice",
    "https://example.com/users/bob"
  ]
}

generator​

Application that created the object.

{
  "generator": {
    "type": "Application",
    "name": "MyApp",
    "url": "https://myapp.example"
  }
}

Addressing Properties​

to​

Primary recipients (public).

{ "to": ["https://www.w3.org/ns/activitystreams#Public"] }

cc​

Secondary recipients (public).

{ "cc": ["https://example.com/users/alice/followers"] }

bto​

Blind primary recipients (hidden).

{ "bto": ["https://example.com/users/admin"] }

bcc​

Blind secondary recipients (hidden).

{ "bcc": ["https://example.com/users/moderator"] }

audience​

Target audience.

{ "audience": "https://lemmy.example/c/technology" }

Relationship Properties​

inReplyTo​

What this object is replying to.

{ "inReplyTo": "https://example.com/notes/123" }

replies​

Collection of replies.

{
  "replies": {
    "type": "Collection",
    "totalItems": 5,
    "first": "https://example.com/notes/123/replies?page=1"
  }
}

tag​

Associated tags (mentions, hashtags, emoji).

{
  "tag": [
    { "type": "Mention", "href": "https://example.com/users/bob", "name": "@bob" },
    { "type": "Hashtag", "href": "https://example.com/tags/fedi", "name": "#fedi" }
  ]
}

attachment​

Attached media or documents.

{
  "attachment": [
    {
      "type": "Document",
      "mediaType": "image/jpeg",
      "url": "https://example.com/image.jpg"
    }
  ]
}

Activity Properties​

actor​

Who performed the activity.

{ "actor": "https://example.com/users/alice" }

object​

What the activity is about.

{ "object": "https://example.com/notes/123" }

target​

Indirect object/destination.

{
  "type": "Add",
  "object": "https://example.com/notes/123",
  "target": "https://example.com/collections/favorites"
}

result​

Outcome of the activity.

{
  "type": "Create",
  "result": {
    "type": "Note",
    "id": "https://example.com/notes/456"
  }
}

origin​

Where the object came from.

{
  "type": "Move",
  "origin": "https://old.example/users/alice"
}

instrument​

Tool used to perform the activity.

{
  "instrument": {
    "type": "Application",
    "name": "Mobile App"
  }
}

Collection Properties​

totalItems​

Total number of items.

{ "totalItems": 150 }

items​

Unordered items.

{ "items": ["https://example.com/1", "https://example.com/2"] }

orderedItems​

Ordered items.

{ "orderedItems": ["https://example.com/3", "https://example.com/2", "https://example.com/1"] }

first​

First page of collection.

{ "first": "https://example.com/collection?page=1" }

last​

Last page of collection.

{ "last": "https://example.com/collection?page=10" }

current​

Current page of collection.

{ "current": "https://example.com/collection?page=5" }

next / prev​

Pagination links.

{
  "next": "https://example.com/collection?page=6",
  "prev": "https://example.com/collection?page=4"
}

partOf​

Parent collection for pages.

{ "partOf": "https://example.com/collection" }

Actor Properties​

inbox​

URL to receive activities.

{ "inbox": "https://example.com/users/alice/inbox" }

outbox​

URL listing published activities.

{ "outbox": "https://example.com/users/alice/outbox" }

following​

Following collection.

{ "following": "https://example.com/users/alice/following" }

followers​

Followers collection.

{ "followers": "https://example.com/users/alice/followers" }

liked​

Liked items collection.

{ "liked": "https://example.com/users/alice/liked" }

preferredUsername​

The @handle part (ASCII, no spaces).

{ "preferredUsername": "alice" }

endpoints​

Service endpoints.

{
  "endpoints": {
    "sharedInbox": "https://example.com/inbox"
  }
}

href​

Target URL.

{ "href": "https://example.com/resource" }

rel​

Link relation.

{ "rel": "self" }

hreflang​

Target language.

{ "hreflang": "en" }

height / width​

Dimensions for media.

{ "height": 1080, "width": 1920 }

Media Properties​

url​

Resource URL(s).

{ "url": "https://example.com/image.jpg" }

Multiple URLs:

{
  "url": [
    { "type": "Link", "href": "https://example.com/image.jpg", "mediaType": "image/jpeg" },
    { "type": "Link", "href": "https://example.com/image.webp", "mediaType": "image/webp" }
  ]
}

icon​

Avatar/icon image.

{
  "icon": {
    "type": "Image",
    "mediaType": "image/png",
    "url": "https://example.com/avatar.png"
  }
}

image​

Header/banner image.

{
  "image": {
    "type": "Image",
    "mediaType": "image/jpeg",
    "url": "https://example.com/header.jpg"
  }
}

preview​

Preview of the object.

{
  "preview": {
    "type": "Image",
    "url": "https://example.com/thumbnail.jpg"
  }
}

Location Properties​

location​

Physical location.

{
  "location": {
    "type": "Place",
    "name": "San Francisco",
    "latitude": 37.7749,
    "longitude": -122.4194
  }
}

latitude / longitude​

Geographic coordinates.

{ "latitude": 37.7749, "longitude": -122.4194 }

altitude / accuracy / radius​

Location precision.

{ "altitude": 100, "accuracy": 10, "radius": 50 }

Special Properties​

sensitive​

Content contains sensitive material.

{ "sensitive": true }

formerType​

Original type of deleted object.

{
  "type": "Tombstone",
  "formerType": "Note",
  "deleted": "2024-01-15T14:00:00Z"
}

deleted​

When the object was deleted.

{ "deleted": "2024-01-15T14:00:00Z" }

Mastodon Extensions​

discoverable​

Show in directory.

{ "discoverable": true }

manuallyApprovesFollowers​

Locked account.

{ "manuallyApprovesFollowers": true }

Pinned posts collection.

{ "featured": "https://example.com/users/alice/collections/featured" }

movedTo / alsoKnownAs​

Account migration.

{
  "movedTo": "https://new.example/users/alice",
  "alsoKnownAs": ["https://old.example/users/alice"]
}

publicKey​

RSA public key for signatures.

{
  "publicKey": {
    "id": "https://example.com/users/alice#main-key",
    "owner": "https://example.com/users/alice",
    "publicKeyPem": "-----BEGIN PUBLIC KEY-----\n...\n-----END PUBLIC KEY-----"
  }
}

Property Quick Reference​

PropertyApplies ToTypeRequired
idAllURIYes*
typeAllString/ArrayYes
actorActivityURI/ObjectYes
objectActivityURI/ObjectUsually
inboxActorURIYes
outboxActorURIYes
contentObjectStringCommon
publishedObjectDateTimeCommon
toObject/ActivityArrayCommon
ccObject/ActivityArrayCommon

*Not required for transient objects

Next Steps​