> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.messageblue.ai/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.messageblue.ai/_mcp/server.

# Create a new group chat and send an intro message

POST https://api.messageblue.ai/createGroupChat
Content-Type: application/json

Creates a new iMessage group from participant handles and sends the intro message. Returns as soon as the Mac agent confirms the UI create+send. `groupId` is best-effort and may be null — for follow-up messages, call /sendGroupMessage with the same `participants` and `force=true` (the agent resolves the chat from participants).

Reference: https://docs.messageblue.ai/api-reference/messages/create-group-chat

## OpenAPI Specification

```yaml
openapi: 3.1.0
info:
  title: swagger
  version: 1.0.0
paths:
  /createGroupChat:
    post:
      operationId: createGroupChat
      summary: Create a new group chat and send an intro message
      description: >-
        Creates a new iMessage group from participant handles and sends the
        intro message. Returns as soon as the Mac agent confirms the UI
        create+send. `groupId` is best-effort and may be null — for follow-up
        messages, call /sendGroupMessage with the same `participants` and
        `force=true` (the agent resolves the chat from participants).
      tags:
        - messages
      parameters:
        - name: X-App-Id
          in: header
          description: >-
            Your MessageBlue App ID, sent in clear on every request. It is
            paired with request signing: each request is also signed with your
            App Secret (see the **Authentication** tag). The App Secret itself
            is NEVER transmitted — it is only the HMAC signing key.
          required: true
          schema:
            type: string
        - name: Idempotency-Key
          in: header
          description: 'Optional: replays return the same cached create result for 24h.'
          required: false
          schema:
            type: string
      responses:
        '200':
          description: Group created
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/CreateGroupChatResponse'
        '400':
          description: Validation error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Unauthorized (HMAC)
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '403':
          description: Agent blocked / not owned
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '409':
          description: >-
            Duplicate content blocked. Codes:
            DUPLICATE_MESSAGE_SAME_NUMBER_DETECTED (per-contact, default 5
            minutes; clears on reply); AGENT_LEVEL_DUPLICATE_MESSAGE_BLOCKED
            (same agent across contacts, default 2 minutes);
            DUPLICATE_MESSAGE_BLOCKED (account/global, default 1 minute).
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '500':
          description: Server error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '502':
          description: Agent failed to create group
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '503':
          description: No agents available / agent offline
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '504':
          description: Agent timeout
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateGroupChatRequest'
servers:
  - url: https://api.messageblue.ai
    description: Production
  - url: http://localhost:8080
    description: Local development
components:
  schemas:
    CreateGroupChatRequest:
      type: object
      properties:
        agentNumber:
          type: string
          description: >-
            Optional agent to create the group from. If omitted, least-mapped
            available agent is chosen.
        participants:
          type: array
          items:
            type: string
          description: At least two distinct phone numbers (E.164) or email handles.
        introMessage:
          type: string
        status_callback:
          type:
            - string
            - 'null'
          format: uri
      required:
        - participants
        - introMessage
      title: CreateGroupChatRequest
    CreateGroupChatResponseData:
      type: object
      properties:
        success:
          type: boolean
        groupId:
          type:
            - string
            - 'null'
          description: >-
            Best-effort chat GUID. Often null because create returns before
            chat.db resolution; use participants + force on sendGroup when
            absent.
        agentNumber:
          type: string
        participantsCount:
          type: integer
        cached:
          type: boolean
          description: True when Idempotency-Key replay returned a cached result.
        introMessage:
          type: string
        participants:
          type: array
          items:
            type: string
      description: Endpoint-specific payload wrapped in a standard success envelope.
      title: CreateGroupChatResponseData
    ResponseMeta:
      type: object
      properties:
        requestId:
          type: string
          format: uuid
        timestamp:
          type: string
          format: date-time
      required:
        - requestId
        - timestamp
      title: ResponseMeta
    CreateGroupChatResponse:
      type: object
      properties:
        ok:
          type: boolean
        data:
          $ref: '#/components/schemas/CreateGroupChatResponseData'
          description: Endpoint-specific payload wrapped in a standard success envelope.
        meta:
          $ref: '#/components/schemas/ResponseMeta'
      required:
        - ok
        - data
        - meta
      title: CreateGroupChatResponse
    FieldError:
      type: object
      properties:
        field:
          type: string
        issue:
          type: string
        message:
          type: string
      required:
        - field
        - issue
        - message
      title: FieldError
    ErrorResponseErrorDetails0:
      type: array
      items:
        $ref: '#/components/schemas/FieldError'
      title: ErrorResponseErrorDetails0
    ErrorResponseErrorDetails:
      oneOf:
        - $ref: '#/components/schemas/ErrorResponseErrorDetails0'
        - type: object
          additionalProperties:
            description: Any type
      description: Field validation errors (array) or domain-specific context (object).
      title: ErrorResponseErrorDetails
    ErrorResponseError:
      type: object
      properties:
        code:
          type: string
        message:
          type: string
        requestId:
          type: string
          format: uuid
        details:
          $ref: '#/components/schemas/ErrorResponseErrorDetails'
          description: Field validation errors (array) or domain-specific context (object).
      required:
        - code
        - message
        - requestId
      title: ErrorResponseError
    ErrorResponse:
      type: object
      properties:
        ok:
          type: boolean
        error:
          $ref: '#/components/schemas/ErrorResponseError'
      required:
        - ok
        - error
      title: ErrorResponse
  securitySchemes:
    appId:
      type: apiKey
      in: header
      name: X-App-Id
      description: >-
        Your MessageBlue App ID, sent in clear on every request. It is paired
        with request signing: each request is also signed with your App Secret
        (see the **Authentication** tag). The App Secret itself is NEVER
        transmitted — it is only the HMAC signing key.

```

## Examples



**Request**

```json
{
  "participants": [
    "+14155551234",
    "jane.doe@example.com"
  ],
  "introMessage": "Welcome to the group!"
}
```

**Response**

```json
{
  "ok": true,
  "data": {
    "success": true,
    "groupId": "iMessage;+;A1B2C3D4-E5F6-7890-1234-56789ABCDEF0",
    "agentNumber": "+14155550123",
    "participantsCount": 2,
    "cached": false,
    "introMessage": "Welcome to the group!",
    "participants": [
      "+14155551234",
      "jane.doe@example.com"
    ]
  },
  "meta": {
    "requestId": "550e8400-e29b-41d4-a716-446655440000",
    "timestamp": "2026-07-10T06:00:00.000Z"
  }
}
```

**SDK Code**

```python
import requests

url = "https://api.messageblue.ai/createGroupChat"

payload = {
    "participants": ["+14155551234", "jane.doe@example.com"],
    "introMessage": "Welcome to the group!"
}
headers = {
    "X-App-Id": "<apiKey>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.json())
```

```javascript
const url = 'https://api.messageblue.ai/createGroupChat';
const options = {
  method: 'POST',
  headers: {'X-App-Id': '<apiKey>', 'Content-Type': 'application/json'},
  body: '{"participants":["+14155551234","jane.doe@example.com"],"introMessage":"Welcome to the group!"}'
};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go
package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.messageblue.ai/createGroupChat"

	payload := strings.NewReader("{\n  \"participants\": [\n    \"+14155551234\",\n    \"jane.doe@example.com\"\n  ],\n  \"introMessage\": \"Welcome to the group!\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("X-App-Id", "<apiKey>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby
require 'uri'
require 'net/http'

url = URI("https://api.messageblue.ai/createGroupChat")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-App-Id"] = '<apiKey>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"participants\": [\n    \"+14155551234\",\n    \"jane.doe@example.com\"\n  ],\n  \"introMessage\": \"Welcome to the group!\"\n}"

response = http.request(request)
puts response.read_body
```

```java
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://api.messageblue.ai/createGroupChat")
  .header("X-App-Id", "<apiKey>")
  .header("Content-Type", "application/json")
  .body("{\n  \"participants\": [\n    \"+14155551234\",\n    \"jane.doe@example.com\"\n  ],\n  \"introMessage\": \"Welcome to the group!\"\n}")
  .asString();
```

```php
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.messageblue.ai/createGroupChat', [
  'body' => '{
  "participants": [
    "+14155551234",
    "jane.doe@example.com"
  ],
  "introMessage": "Welcome to the group!"
}',
  'headers' => [
    'Content-Type' => 'application/json',
    'X-App-Id' => '<apiKey>',
  ],
]);

echo $response->getBody();
```

```csharp
using RestSharp;

var client = new RestClient("https://api.messageblue.ai/createGroupChat");
var request = new RestRequest(Method.POST);
request.AddHeader("X-App-Id", "<apiKey>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"participants\": [\n    \"+14155551234\",\n    \"jane.doe@example.com\"\n  ],\n  \"introMessage\": \"Welcome to the group!\"\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "X-App-Id": "<apiKey>",
  "Content-Type": "application/json"
]
let parameters = [
  "participants": ["+14155551234", "jane.doe@example.com"],
  "introMessage": "Welcome to the group!"
] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://api.messageblue.ai/createGroupChat")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```