## Join a chat

`POST /v1/chats/:dialogId/join`

The current user joins a chat that can be entered without an invitation — the v2 messenger method `im.v2.Chat.join`. This works for an open chat or channel, an Open Channel, the general chat of the Bitrix24 account, a comment chat, an external chat or an open collab. Bitrix24 posts a system message about the join in the chat.

## Parameters

| Parameter | Type | Required | Description |
|----------|-----|:-----:|---------|
| `dialogId` (path) | string | yes | Chat ID as `chatN`, for example `chat42` |

The endpoint accepts no query parameters and no request body: any parameter or body field is rejected with `400 INVALID_PARAMS` before any call to Bitrix24.

## Examples

### curl — personal key

```bash
curl -X POST https://vibecode.bitrix24.com/v1/chats/chat42/join \
  -H "X-Api-Key: YOUR_API_KEY"
```

### curl — OAuth application

```bash
curl -X POST https://vibecode.bitrix24.com/v1/chats/chat42/join \
  -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/chat42/join', {
  method: 'POST',
  headers: { 'X-Api-Key': 'YOUR_API_KEY' },
})

const { success, data } = await res.json()
console.log('Joined:', data.result) // true
```

### JavaScript — OAuth application

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/chat42/join', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_APP_KEY',
    'Authorization': 'Bearer USER_SESSION_TOKEN',
  },
})

const { success, data } = await res.json()
```

## Response fields

| Field | Type | Description |
|------|-----|---------|
| `success` | boolean | Always `true` on success |
| `data.result` | boolean | `true` — the user is in the chat |

## Response example

```json
{
  "success": true,
  "data": {
    "result": true
  }
}
```

## Error response example

422 — a chat of this type cannot be joined on your own:

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

## Errors

| HTTP | Code | Description |
|------|-----|---------|
| 400 | `INVALID_PARAMS` | A query parameter or a body field was sent — the endpoint accepts neither |
| 404 | `ENTITY_NOT_FOUND` | Bitrix24 returned "not found"; the portal code is in `error.b24Code` |
| 422 | `BITRIX_ERROR` | Bitrix24 returned an error; the portal code is in `error.b24Code`. `WRONG_MESSAGE_TYPE` — a chat of this type cannot be joined on your own, `CHAT_NOT_FOUND` — the chat does not exist on the portal |
| 502 | `ME_ALIAS_RESOLUTION_FAILED` | Failed to resolve the user when using the `me` alias |
| 403 | `BITRIX_ACCESS_DENIED` | Bitrix24 refused with the `ACCESS_DENIED` code: the user is not allowed to join chats or has no access to this chat |
| 403 | `SCOPE_DENIED` | The API key does not have the `im` scope |
| 403 | `WRITE_BLOCKED_READONLY_KEY` | The key is read-only — see [access rights](/docs/access-rights) |
| 401 | `TOKEN_MISSING` | The API key has no Bitrix24 tokens configured |

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

## Known specifics

**A closed group chat is by invitation only.** A regular group chat without the open flag answers `422 BITRIX_ERROR` with `error.b24Code` `WRONG_MESSAGE_TYPE`: members are added to it by a member allowed to invite — [adding members](/docs/chats/members/add). The `searchable: "Y"` field makes a chat open when it is [created in the v2 mode](/docs/chats/management/create).

**Joining again.** If you are already a member of a chat that can be entered without an invitation, the answer is the same — `data.result: true`. The type check comes before the membership check: in a closed chat, even a member of that chat gets `WRONG_MESSAGE_TYPE`.

## See also

- [Chat management](/docs/chats/management)
- [Leave a chat](/docs/chats/management/leave)
- [Add members](/docs/chats/members/add)