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+---
+title: ActivityPub compliance
+description: What objects and properties of the ActivityPub spec Mastodon supports
+menu:
+  docs:
+    parent: administration
+    weight: 5
+---
+
+## APIs
+
+- Mastodon supports the server-to-server part of the ActivityPub spec.
+- It implements the HTTP signatures spec for authentication of inbox deliveries.
+- Mastodon also supports Linked Data Signatures for forwarded payloads.
+
+## Restrictions
+
+- Mastodon requires all object IDs to use the HTTPS schema.
+- Mastodon also requires servers to offer a WebFinger endpoint for converting username/domain pairs into actors.
+- Mastodon accepts `Application`, `Group`, `Organization`, `Person`, and `Service` as valid types for actors.
+- Mastodon requires activities attributed to an actor to have an ID on the same host as the actor.
+
+## Activities
+
+|Supported activity|Supported objects|Notes|
+|------------------|-----------------|-----|
+|`Accept`|`Follow`|The `object` of the `Follow` is expected to be an actor from the receiving server|
+|`Add`|`Note`|Only the actor's own objects and only to the actor's featured collection URI as `target`|
+|`Announce`|`Object`|Any object supported by `Create` is supported here|
+|`Block`|`Object`|The `object` is expected to point to an actor from the receiving server|
+|`Create`|`Note`, `Article`, `Image`, `Video`||
+|`Delete`|`Object`|Only the actor's own objects will be deleted, such as anything created before
+|`Flag`|`Object`|The `object` is expected to point to one or multiple objects originating on the receiving server|
+|`Follow`|`Object`|The `object` is expected to point to an actor from the receiving server|
+|`Like`|`Object`|The `object` is expected to be something created on the receiving server|
+|`Move`|`Object`|Only the actor's own actor object can be moved to another actor object at `target`|
+|`Reject`|`Follow`|The `object` of the `Follow` is expected to be an actor from the receiving server|
+|`Remove`|`Note`|Only the actor's own objects and only from the actor's featured collection URI as `origin`|
+|`Undo`|`Accept`, `Announce`, `Block`, `Follow`, `Like`||
+|`Update`|`Object`|Only the actor's own actor object can be updated|
+
+## Extensions
+### Featured collection
+
+What is known in Mastodon as "pinned toots", or statuses that are always featured at the top of people's profiles, is implemented using an extra property `featured` on the actor object that points to a `Collection` of objects. Example:
+
+```json
+{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+        
+    {
+      "toot": "http://joinmastodon.org/ns#",
+      "featured": {
+        "@id": "toot:featured",
+        "@type": "@id"
+      }
+    }
+  ],
+
+  "id": "https://example.com/@alice",
+  "type": "Person",
+  "featured": "https://example.com/@alice/collections/featured"
+}
+```
+
+### Custom emojis
+
+Mastodon supports arbitrary emojis, that is, small images uploaded by admins and invokable via shortcodes. For this, an `Emoji` type is used. These emojis are listed in the `tag` property just like `Mention` and `Hashtag` objects, since they are entities that affect how the text is rendered. Example:
+
+```json
+{
+  "@context": [
+    "https://www.w3.org/ns/activitystreams",
+        
+    {
+      "toot": "http://joinmastodon.org/ns#",
+      "Emoji": "toot:Emoji"
+    }
+  ],
+
+  "id": "https://example.com/@alice/hello-world",
+  "type": "Note",
+  "content": "Hello world :Kappa:",
+  "tag": [
+    {
+      "id": "https://example.com/emoji/123",
+      "type": "Emoji",
+      "name": ":Kappa:",
+      "icon": {
+        "type": "Image",
+        "mediaType": "image/png",
+        "url": "https://example.com/files/kappa.png"
+      }
+    }
+  ]
+}
+```
+
+### Focal points
+
+Mastodon supports setting a focal point on uploaded images, so that wherever that image is displayed, the focal point stays in view. This is implemented using an extra property `focalPoint` on the `Image` objects. The property is simply an array of two floating points between 0 and 1. Example:
+