## Who viewed a message

`GET /v1/chats/messages/:messageId/viewers`

Returns the views of a message — who saw it and when — using the v2 messenger method `im.v2.Chat.Message.tailViewers`. The chat is determined from the message, so no `dialogId` is needed. Views come in pages, from newest to oldest by default.

## Parameters

| Parameter | Type | Required | Default | Description |
|----------|-----|:-----:|-----------|---------|
| `messageId` (path) | number | yes | — | Message ID, a positive integer — from the [chat feed](/docs/chats/messages/list) (`GET /v1/chats/:dialogId/messages`) or from the response of [sending](/docs/chats/messages/send) |
| `lastId` (query) | number | no | — | Cursor: the `id` of the last view on the previous page. The bound is exclusive |
| `order` (query) | string | no | `desc` | `desc` — from newest views to oldest, `asc` — from oldest to newest |
| `limit` (query) | number | no | 50 | Views per page. From 1 to 200: an out-of-range value is clamped and echoed in `meta.requestedLimit` and `meta.appliedLimit` |

Any other parameter or a repeated parameter is rejected with `400 INVALID_PARAMS`.

## Examples

### curl — personal key

```bash
curl "https://vibecode.bitrix24.com/v1/chats/messages/1002/viewers?limit=20" \
  -H "X-Api-Key: YOUR_API_KEY"
```

### curl — OAuth application

```bash
curl "https://vibecode.bitrix24.com/v1/chats/messages/1002/viewers?limit=20" \
  -H "X-Api-Key: YOUR_APP_KEY" \
  -H "Authorization: Bearer USER_SESSION_TOKEN"
```

### JavaScript — personal key

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/messages/1002/viewers?limit=20', {
  headers: { 'X-Api-Key': 'YOUR_API_KEY' },
})

const { data } = await res.json()
console.log('Viewed by:', data.views.map((v) => v.userId))
```

### JavaScript — OAuth application

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/messages/1002/viewers?limit=20', {
  headers: {
    'X-Api-Key': 'YOUR_APP_KEY',
    'Authorization': 'Bearer USER_SESSION_TOKEN',
  },
})

const { data } = await res.json()
console.log('Viewed by:', data.views.map((v) => v.userId))
```

## Response fields

| Field | Type | Description |
|------|-----|---------|
| `success` | boolean | Always `true` on success |
| `data.views` | array | Views on the page |
| `data.views[].id` | number | View ID — the `lastId` cursor for the next page |
| `data.views[].messageId` | number | Message ID |
| `data.views[].userId` | number | ID of the user who viewed the message |
| `data.views[].dateView` | string | View time (ISO 8601) |
| `data.users` | array | Profiles of the users in `views` |
| `data.hasNextPage` | boolean | `false` — no more views in the chosen direction |
| `meta.requestedLimit` | number | The passed `limit` value, present when it falls outside the range from 1 to 200 |
| `meta.appliedLimit` | number | The applied `limit` value |

## Response example

```json
{
  "success": true,
  "data": {
    "views": [
      {
        "id": 9001,
        "messageId": 1002,
        "userId": 5,
        "dateView": "2026-09-20T10:05:00+00:00"
      }
    ],
    "users": [
      {
        "id": 5,
        "active": true,
        "name": "John Smith",
        "firstName": "John",
        "lastName": "Smith",
        "type": "user"
      }
    ],
    "hasNextPage": false
  }
}
```

## Error response example

422 — the message does not exist in the Bitrix24 account:

```json
{
  "success": false,
  "error": {
    "code": "BITRIX_ERROR",
    "message": "MESSAGE_NOT_FOUND",
    "b24Code": "MESSAGE_NOT_FOUND"
  }
}
```

## Errors

| HTTP | Code | Description |
|------|-----|---------|
| 400 | `INVALID_PARAMS` | `messageId` is not a positive integer, or the request has a parameter outside the allowed set (`lastId`, `order`, `limit`), a repeated parameter or an invalid value. Checked before any call to Bitrix24 |
| 404 | `ENTITY_NOT_FOUND` | Bitrix24 returned the `NOT_FOUND` code; the portal code is in `error.b24Code` |
| 422 | `BITRIX_ERROR` | Bitrix24 returned an error; the portal code is in `error.b24Code`. A missing message lands here too: `MESSAGE_NOT_FOUND` |
| 403 | `BITRIX_ACCESS_DENIED` | The user has no access to the chat of the message — Bitrix24 refused with the `ACCESS_DENIED` code |
| 403 | `WRITE_BLOCKED_READONLY_KEY` | A `READONLY` or `PORTAL_READONLY` key is refused before the Bitrix24 call because this operation may add the caller to the chat |
| 403 | `SCOPE_DENIED` | The API key does not have the `im` scope |
| 401 | `TOKEN_MISSING` | The API key has no Bitrix24 tokens configured |

Full list of common API errors — [Errors](/docs/errors).

## Known specifics

**The call may make you a member.** Like [message context](/docs/chats/messages/context), it may conditionally add the caller to the chat. Because the call may add the caller to the chat, `READONLY` and `PORTAL_READONLY` keys receive `403 WRITE_BLOCKED_READONLY_KEY` before Bitrix24 is called. The operation does not mark the message read. The user's Bitrix24 access and the `im` scope still apply.

**Paging.** The next page is the same request with `lastId` equal to the `id` of the last view in `data.views`, as long as `data.hasNextPage` is `true`.

## See also

- [Messages around a message](/docs/chats/messages/context)
- [Mark as read](/docs/chats/messages/read)