akkoma/test/fixtures/activitypub-client-post-activity.json

{
  "@context": ["https://www.w3.org/ns/activitystreams", {"@language": "en-GB"}],
  "type": "Create",
  "object": {
    "type": "Note",
    "content": "It's a note"
  },
  "to": ["https://www.w3.org/ns/activitystreams#Public"]
}