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Hashtags and JSON-LD

The examples here are various variations of creating the Hashtag element in the tag list. These variations can be useful in understanding how strict an application sees JSON-LD.

Hashtags are a good illustration of JSON-LD parsing as Hashtag is not part of the ActivityStreams vocabulary.

All examples except the first are questionable, and probably should not be used when publishing to the Fediverse. The examples marked with ⚠️ are expected to fail with a JSON-LD parser. The examples using as:Hashtag are expected to fail with a JSON only parser.

Examples

Example 1

activity
{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://misskey/users/ag0mqqelszbk0003"
  ],
  "id": "http://pasture-one-actor/activity/rJCmNu8Y24c",
  "published": "2025-12-08T11:27:24Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://misskey/users/ag0mqqelszbk0003"
    ],
    "id": "http://pasture-one-actor/object/AIDotU28akY",
    "published": "2025-12-08T11:27:24Z",
    "content": "text",
    "tag": [
      {
        "type": "Hashtag",
        "name": "#test"
      }
    ]
  }
}
misskey
{
  "id": "ag0msleogsyv000i",
  "createdAt": "2025-12-08T11:27:24.000Z",
  "userId": "ag0msgbpgsyv0003",
  "user": {
    "id": "ag0msgbpgsyv0003",
    "name": "Test Actor",
    "username": "actor",
    "host": "pasture-one-actor",
    "avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
    "avatarBlurhash": null,
    "avatarDecorations": [],
    "isBot": false,
    "isCat": false,
    "instance": {
      "name": null,
      "softwareName": null,
      "softwareVersion": null,
      "iconUrl": null,
      "faviconUrl": null,
      "themeColor": null
    },
    "emojis": {},
    "onlineStatus": "unknown"
  },
  "text": "text",
  "cw": null,
  "visibility": "public",
  "localOnly": false,
  "reactionAcceptance": null,
  "renoteCount": 0,
  "repliesCount": 0,
  "reactionCount": 0,
  "reactions": {},
  "reactionEmojis": {},
  "emojis": {},
  "tags": [
    "test"
  ],
  "fileIds": [],
  "files": [],
  "replyId": null,
  "renoteId": null,
  "uri": "http://pasture-one-actor/object/AIDotU28akY",
  "clippedCount": 0
}
mitra
{
  "id": "019afdb3-af17-9539-874c-94f0505c279b",
  "uri": "http://pasture-one-actor/object/7bTeRtMF7V0",
  "url": "http://pasture-one-actor/object/7bTeRtMF7V0",
  "created_at": "2025-12-08T11:23:21.000Z",
  "edited_at": null,
  "account": {
    "id": "019afdb3-61e8-e91d-00a9-6305e55bfa40",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "actor_id": "http://pasture-one-actor/actor",
    "url": "http://pasture-one-actor/actor",
    "display_name": "Test Actor",
    "created_at": "2025-12-08T11:23:03.016Z",
    "note": "",
    "avatar": "http://mitra/api/v1/accounts/identicon?input=http://pasture-one-actor/actor",
    "header": "http://mitra/api/v1/accounts/identicon",
    "locked": false,
    "mention_policy": "none",
    "bot": false,
    "discoverable": true,
    "identity_proofs": [],
    "payment_options": [],
    "fields": [],
    "emojis": [],
    "followers_count": 0,
    "following_count": 0,
    "subscribers_count": 0,
    "statuses_count": 14,
    "source": null,
    "role": null,
    "authentication_methods": null,
    "client_config": null
  },
  "content": "text",
  "language": null,
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "visibility": "public",
  "sensitive": false,
  "spoiler_text": "",
  "pinned": false,
  "replies_count": 0,
  "favourites_count": 0,
  "reblogs_count": 0,
  "poll": null,
  "media_attachments": [],
  "quote": null,
  "mentions": [
    {
      "id": "019afdb2-1a7f-a0f1-3155-3a8b0a2e5dc1",
      "username": "admin",
      "acct": "admin",
      "url": "http://mitra/users/admin"
    }
  ],
  "tags": [
    {
      "name": "test",
      "url": "http://mitra/collections/tags/test"
    }
  ],
  "emojis": [],
  "favourited": false,
  "reblogged": false,
  "bookmarked": false,
  "pleroma": {
    "emoji_reactions": [],
    "in_reply_to_account_acct": null,
    "parent_visible": true,
    "quote": null,
    "quote_visible": true
  },
  "hidden": false,
  "ipfs_cid": null,
  "links": []
}

Example 2

activity
{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://misskey/users/ag0mqqelszbk0003"
  ],
  "id": "http://pasture-one-actor/activity/-GGvvpkrC4Y",
  "published": "2025-12-08T11:27:24Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://misskey/users/ag0mqqelszbk0003"
    ],
    "id": "http://pasture-one-actor/object/C90YSTasVvU",
    "published": "2025-12-08T11:27:24Z",
    "content": "using as:Hashtag",
    "tag": [
      {
        "type": "as:Hashtag",
        "name": "#test"
      }
    ]
  }
}
misskey
{
  "id": "ag0msleogsyv000k",
  "createdAt": "2025-12-08T11:27:24.000Z",
  "userId": "ag0msgbpgsyv0003",
  "user": {
    "id": "ag0msgbpgsyv0003",
    "name": "Test Actor",
    "username": "actor",
    "host": "pasture-one-actor",
    "avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
    "avatarBlurhash": null,
    "avatarDecorations": [],
    "isBot": false,
    "isCat": false,
    "instance": {
      "name": null,
      "softwareName": null,
      "softwareVersion": null,
      "iconUrl": null,
      "faviconUrl": null,
      "themeColor": null
    },
    "emojis": {},
    "onlineStatus": "unknown"
  },
  "text": "using as:Hashtag",
  "cw": null,
  "visibility": "public",
  "localOnly": false,
  "reactionAcceptance": null,
  "renoteCount": 0,
  "repliesCount": 0,
  "reactionCount": 0,
  "reactions": {},
  "reactionEmojis": {},
  "emojis": {},
  "fileIds": [],
  "files": [],
  "replyId": null,
  "renoteId": null,
  "uri": "http://pasture-one-actor/object/C90YSTasVvU",
  "clippedCount": 0
}
mitra
{
  "id": "019afdb3-b4f3-93f7-6b49-a97b10ca26e6",
  "uri": "http://pasture-one-actor/object/nOWx7L7LU4g",
  "url": "http://pasture-one-actor/object/nOWx7L7LU4g",
  "created_at": "2025-12-08T11:23:23.000Z",
  "edited_at": null,
  "account": {
    "id": "019afdb3-61e8-e91d-00a9-6305e55bfa40",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "actor_id": "http://pasture-one-actor/actor",
    "url": "http://pasture-one-actor/actor",
    "display_name": "Test Actor",
    "created_at": "2025-12-08T11:23:03.016Z",
    "note": "",
    "avatar": "http://mitra/api/v1/accounts/identicon?input=http://pasture-one-actor/actor",
    "header": "http://mitra/api/v1/accounts/identicon",
    "locked": false,
    "mention_policy": "none",
    "bot": false,
    "discoverable": true,
    "identity_proofs": [],
    "payment_options": [],
    "fields": [],
    "emojis": [],
    "followers_count": 0,
    "following_count": 0,
    "subscribers_count": 0,
    "statuses_count": 15,
    "source": null,
    "role": null,
    "authentication_methods": null,
    "client_config": null
  },
  "content": "using as:Hashtag",
  "language": null,
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "visibility": "public",
  "sensitive": false,
  "spoiler_text": "",
  "pinned": false,
  "replies_count": 0,
  "favourites_count": 0,
  "reblogs_count": 0,
  "poll": null,
  "media_attachments": [],
  "quote": null,
  "mentions": [
    {
      "id": "019afdb2-1a7f-a0f1-3155-3a8b0a2e5dc1",
      "username": "admin",
      "acct": "admin",
      "url": "http://mitra/users/admin"
    }
  ],
  "tags": [],
  "emojis": [],
  "favourited": false,
  "reblogged": false,
  "bookmarked": false,
  "pleroma": {
    "emoji_reactions": [],
    "in_reply_to_account_acct": null,
    "parent_visible": true,
    "quote": null,
    "quote_visible": true
  },
  "hidden": false,
  "ipfs_cid": null,
  "links": []
}

Example 3

activity
{
  "@context": [
    "https://www.w3.org/ns/activitystreams",
    {
      "Hashtag": "as:Hashtag",
      "sensitive": "as:sensitive"
    }
  ],
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://misskey/users/ag0mqqelszbk0003"
  ],
  "id": "http://pasture-one-actor/activity/TH-maFVUyIU",
  "published": "2025-12-08T11:27:25Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://misskey/users/ag0mqqelszbk0003"
    ],
    "id": "http://pasture-one-actor/object/5iLXuJD-efI",
    "published": "2025-12-08T11:27:25Z",
    "content": "no type \u26a0\ufe0f ",
    "tag": [
      {
        "name": "#test"
      }
    ]
  }
}
misskey
{
  "id": "ag0msm6ggsyv000l",
  "createdAt": "2025-12-08T11:27:25.000Z",
  "userId": "ag0msgbpgsyv0003",
  "user": {
    "id": "ag0msgbpgsyv0003",
    "name": "Test Actor",
    "username": "actor",
    "host": "pasture-one-actor",
    "avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
    "avatarBlurhash": null,
    "avatarDecorations": [],
    "isBot": false,
    "isCat": false,
    "instance": {
      "name": null,
      "softwareName": null,
      "softwareVersion": null,
      "iconUrl": null,
      "faviconUrl": null,
      "themeColor": null
    },
    "emojis": {},
    "onlineStatus": "unknown"
  },
  "text": "no type \u26a0\ufe0f",
  "cw": null,
  "visibility": "public",
  "localOnly": false,
  "reactionAcceptance": null,
  "renoteCount": 0,
  "repliesCount": 0,
  "reactionCount": 0,
  "reactions": {},
  "reactionEmojis": {},
  "emojis": {},
  "fileIds": [],
  "files": [],
  "replyId": null,
  "renoteId": null,
  "uri": "http://pasture-one-actor/object/5iLXuJD-efI",
  "clippedCount": 0
}
mitra
{
  "id": "019afdb3-bad2-93b9-0412-def6a546ca90",
  "uri": "http://pasture-one-actor/object/HbvOpfw_H_U",
  "url": "http://pasture-one-actor/object/HbvOpfw_H_U",
  "created_at": "2025-12-08T11:23:25.000Z",
  "edited_at": null,
  "account": {
    "id": "019afdb3-61e8-e91d-00a9-6305e55bfa40",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "actor_id": "http://pasture-one-actor/actor",
    "url": "http://pasture-one-actor/actor",
    "display_name": "Test Actor",
    "created_at": "2025-12-08T11:23:03.016Z",
    "note": "",
    "avatar": "http://mitra/api/v1/accounts/identicon?input=http://pasture-one-actor/actor",
    "header": "http://mitra/api/v1/accounts/identicon",
    "locked": false,
    "mention_policy": "none",
    "bot": false,
    "discoverable": true,
    "identity_proofs": [],
    "payment_options": [],
    "fields": [],
    "emojis": [],
    "followers_count": 0,
    "following_count": 0,
    "subscribers_count": 0,
    "statuses_count": 16,
    "source": null,
    "role": null,
    "authentication_methods": null,
    "client_config": null
  },
  "content": "no type \u26a0\ufe0f ",
  "language": null,
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "visibility": "public",
  "sensitive": false,
  "spoiler_text": "",
  "pinned": false,
  "replies_count": 0,
  "favourites_count": 0,
  "reblogs_count": 0,
  "poll": null,
  "media_attachments": [],
  "quote": null,
  "mentions": [
    {
      "id": "019afdb2-1a7f-a0f1-3155-3a8b0a2e5dc1",
      "username": "admin",
      "acct": "admin",
      "url": "http://mitra/users/admin"
    }
  ],
  "tags": [
    {
      "name": "test",
      "url": "http://mitra/collections/tags/test"
    }
  ],
  "emojis": [],
  "favourited": false,
  "reblogged": false,
  "bookmarked": false,
  "pleroma": {
    "emoji_reactions": [],
    "in_reply_to_account_acct": null,
    "parent_visible": true,
    "quote": null,
    "quote_visible": true
  },
  "hidden": false,
  "ipfs_cid": null,
  "links": []
}

Example 4

activity
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://misskey/users/ag0mqqelszbk0003"
  ],
  "id": "http://pasture-one-actor/activity/rvko8WwIJak",
  "published": "2025-12-08T11:27:26Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://misskey/users/ag0mqqelszbk0003"
    ],
    "id": "http://pasture-one-actor/object/8bfbM7Ozats",
    "published": "2025-12-08T11:27:26Z",
    "@context": "https://www.w3.org/ns/activitystreams",
    "content": "Hashtag not in @context \u26a0\ufe0f ",
    "tag": [
      {
        "type": "Hashtag",
        "name": "#test"
      }
    ]
  }
}
misskey
{
  "id": "ag0msmy8gsyv000m",
  "createdAt": "2025-12-08T11:27:26.000Z",
  "userId": "ag0msgbpgsyv0003",
  "user": {
    "id": "ag0msgbpgsyv0003",
    "name": "Test Actor",
    "username": "actor",
    "host": "pasture-one-actor",
    "avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
    "avatarBlurhash": null,
    "avatarDecorations": [],
    "isBot": false,
    "isCat": false,
    "instance": {
      "name": null,
      "softwareName": null,
      "softwareVersion": null,
      "iconUrl": null,
      "faviconUrl": null,
      "themeColor": null
    },
    "emojis": {},
    "onlineStatus": "unknown"
  },
  "text": "Hashtag not in @context \u26a0\ufe0f",
  "cw": null,
  "visibility": "public",
  "localOnly": false,
  "reactionAcceptance": null,
  "renoteCount": 0,
  "repliesCount": 0,
  "reactionCount": 0,
  "reactions": {},
  "reactionEmojis": {},
  "emojis": {},
  "tags": [
    "test"
  ],
  "fileIds": [],
  "files": [],
  "replyId": null,
  "renoteId": null,
  "uri": "http://pasture-one-actor/object/8bfbM7Ozats",
  "clippedCount": 0
}
mitra
{
  "id": "019afdb3-c0ab-1ed9-9299-0c71c8e31821",
  "uri": "http://pasture-one-actor/object/AbTN6C4fKJ0",
  "url": "http://pasture-one-actor/object/AbTN6C4fKJ0",
  "created_at": "2025-12-08T11:23:26.000Z",
  "edited_at": null,
  "account": {
    "id": "019afdb3-61e8-e91d-00a9-6305e55bfa40",
    "username": "actor",
    "acct": "actor@pasture-one-actor",
    "actor_id": "http://pasture-one-actor/actor",
    "url": "http://pasture-one-actor/actor",
    "display_name": "Test Actor",
    "created_at": "2025-12-08T11:23:03.016Z",
    "note": "",
    "avatar": "http://mitra/api/v1/accounts/identicon?input=http://pasture-one-actor/actor",
    "header": "http://mitra/api/v1/accounts/identicon",
    "locked": false,
    "mention_policy": "none",
    "bot": false,
    "discoverable": true,
    "identity_proofs": [],
    "payment_options": [],
    "fields": [],
    "emojis": [],
    "followers_count": 0,
    "following_count": 0,
    "subscribers_count": 0,
    "statuses_count": 17,
    "source": null,
    "role": null,
    "authentication_methods": null,
    "client_config": null
  },
  "content": "Hashtag not in @context \u26a0\ufe0f ",
  "language": null,
  "in_reply_to_id": null,
  "in_reply_to_account_id": null,
  "reblog": null,
  "visibility": "public",
  "sensitive": false,
  "spoiler_text": "",
  "pinned": false,
  "replies_count": 0,
  "favourites_count": 0,
  "reblogs_count": 0,
  "poll": null,
  "media_attachments": [],
  "quote": null,
  "mentions": [
    {
      "id": "019afdb2-1a7f-a0f1-3155-3a8b0a2e5dc1",
      "username": "admin",
      "acct": "admin",
      "url": "http://mitra/users/admin"
    }
  ],
  "tags": [
    {
      "name": "test",
      "url": "http://mitra/collections/tags/test"
    }
  ],
  "emojis": [],
  "favourited": false,
  "reblogged": false,
  "bookmarked": false,
  "pleroma": {
    "emoji_reactions": [],
    "in_reply_to_account_acct": null,
    "parent_visible": true,
    "quote": null,
    "quote_visible": true
  },
  "hidden": false,
  "ipfs_cid": null,
  "links": []
}

Example 5

activity
{
  "@context": "https://www.w3.org/ns/activitystreams",
  "type": "Create",
  "actor": "http://pasture-one-actor/actor",
  "to": [
    "https://www.w3.org/ns/activitystreams#Public",
    "http://misskey/users/ag0mqqelszbk0003"
  ],
  "id": "http://pasture-one-actor/activity/TAHk-dRzM3c",
  "published": "2025-12-08T11:27:26Z",
  "object": {
    "type": "Note",
    "attributedTo": "http://pasture-one-actor/actor",
    "to": [
      "https://www.w3.org/ns/activitystreams#Public",
      "http://misskey/users/ag0mqqelszbk0003"
    ],
    "id": "http://pasture-one-actor/object/ZFerfKZO5Kc",
    "published": "2025-12-08T11:27:26Z",
    "@context": "https://www.w3.org/ns/activitystreams",
    "content": "Hashtag not in @context; as:Hashtag",
    "tag": [
      {
        "type": "as:Hashtag",
        "name": "#test"
      }
    ]
  }
}
misskey
{
  "id": "ag0msmy8gsyv000n",
  "createdAt": "2025-12-08T11:27:26.000Z",
  "userId": "ag0msgbpgsyv0003",
  "user": {
    "id": "ag0msgbpgsyv0003",
    "name": "Test Actor",
    "username": "actor",
    "host": "pasture-one-actor",
    "avatarUrl": "http://misskey/identicon/actor@pasture-one-actor",
    "avatarBlurhash": null,
    "avatarDecorations": [],
    "isBot": false,
    "isCat": false,
    "instance": {
      "name": null,
      "softwareName": null,
      "softwareVersion": null,
      "iconUrl": null,
      "faviconUrl": null,
      "themeColor": null
    },
    "emojis": {},
    "onlineStatus": "unknown"
  },
  "text": "Hashtag not in @context; as:Hashtag",
  "cw": null,
  "visibility": "public",
  "localOnly": false,
  "reactionAcceptance": null,
  "renoteCount": 0,
  "repliesCount": 0,
  "reactionCount": 0,
  "reactions": {},
  "reactionEmojis": {},
  "emojis": {},
  "fileIds": [],
  "files": [],
  "replyId": null,
  "renoteId": null,
  "uri": "http://pasture-one-actor/object/ZFerfKZO5Kc",
  "clippedCount": 0
}
mitra
{
  "id": "019afdb3-c684-c1e6-8656-447028fd4635",
  "uri": "http://pasture-one-actor/object/VrPKj0EVFZk",
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