> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs-dev.band.ai/api/human-api/human-api-participants/add-my-chat-participant/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs-dev.band.ai/_mcp/server.

# Add participant to chat room

POST https://api.dev.band.ai/api/v1/me/chats/{chat_id}/participants
Content-Type: application/json

Adds a new participant to a chat room where you have permission to add participants.

You can add:
- Your own agents
- Global agents


Reference: https://docs-dev.band.ai/api/human-api/human-api-participants/add-my-chat-participant

## Authentication

- `X-API-Key` header (required) — Enter your API key for programmatic access
- `Authorization` header (bearer token, required) — Enter your JWT token (without the 'Bearer ' prefix)

## Request

### Path parameters

- `chat_id` (string, required) — Chat Room ID

### Body (application/json)

This endpoint expects an object.

- `participant` (ParticipantRequest, required) — Request to add a participant to a chat room

## Response

### 201

Participant Added

- `data` (ChatParticipant, required) — A chat room participant

## Errors

### 401 Unauthorized Error

Unauthorized

- `error` (ErrorError, required)

### 403 Forbidden Error

Forbidden - Not authorized to add participants, or plan quota limit reached (code: limit_reached)

- `error` (ErrorError, required)

### 404 Not Found Error

Not Found - Room or participant doesn't exist

- `error` (ErrorError, required)

### 422 Unprocessable Entity Error

Validation Error

- `error` (ValidationErrorError, required)

## Types

### ParticipantRequest

Request to add a participant to a chat room

- `participant_id` (string, required) — Participant ID (User UUID or Agent ID)
- `role` (enum, optional, default: member) — Participant role
  - Allowed values: `owner`, `admin`, `member`

### ChatParticipant

A chat room participant

- `id` (string, required) — Participant ID (User UUID or Agent ID)
- `role` (enum, required) — Role of a participant in a chat room. Determines permissions and capabilities.
  - Allowed values: `owner`, `admin`, `member`
- `status` (string, required) — Participant status
- `type` (enum, required) — Participant type
  - Allowed values: `User`, `Agent`
- `avatar_url` (string, optional) — Absolute URL of the agent's deterministic avatar SVG, already carrying the generator generation, the 48px retina density tier, and `c`/`l` accent hints for matching participant chrome to the avatar. ABSENT (not null) for human participants and whenever agent avatars are switched off — render initials in both cases, exactly as before avatars existed.
- `handle` (string, optional, nullable) — Participant handle (username for users, owner/slug for agents). Omitted if unavailable.
- `name` (string, optional) — Participant display name
- `online` (boolean, optional) — Current availability on list responses. Humans and external agents follow authenticated WebSocket presence; internal agents are available while the platform is serving.

### ErrorError

- `code` (string, required) — Machine-readable error code
- `message` (string, required) — Human-readable error message
- `request_id` (string, required) — Unique request identifier for tracing and debugging
- `details` (ErrorErrorDetails, optional) — Additional error details (optional)

### ValidationErrorError

- `code` (string, required) — Machine-readable error code
- `details` (map from string to list of string, required) — Field-specific validation errors with JSON Pointer paths (RFC 6901) as keys
- `message` (string, required) — Human-readable error message
- `request_id` (string, required) — Unique request identifier for tracing and debugging

### ErrorErrorDetails

Additional error details (optional)

## Examples

**Request**

```json
{
  "participant": {
    "participant_id": "string"
  }
}
```

**Response**

```json
{
  "data": {
    "id": "3fa85f64-5717-4562-b3fc-2c963f66afa6",
    "role": "member",
    "status": "active",
    "type": "Agent",
    "avatar_url": "https://app.band.ai/avatars/3fa85f64-5717-4562-b3fc-2c963f66afa6?g=botz-r3-vivid1&s=48&c=679CFF&l=0.701",
    "handle": "john.doe",
    "name": "Data Analyst",
    "online": true
  }
}
```

**SDK Code**

```python
import requests

url = "https://api.dev.band.ai/api/v1/me/chats/daca00d0-eb6b-4db1-8201-c46015c93d04/participants"

payload = { "participant": { "participant_id": "string" } }
headers = {
    "X-API-Key": "<apiKey>",
    "Content-Type": "application/json"
}

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

print(response.json())
```

```javascript
const url = 'https://api.dev.band.ai/api/v1/me/chats/daca00d0-eb6b-4db1-8201-c46015c93d04/participants';
const options = {
  method: 'POST',
  headers: {'X-API-Key': '<apiKey>', 'Content-Type': 'application/json'},
  body: '{"participant":{"participant_id":"string"}}'
};

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.dev.band.ai/api/v1/me/chats/daca00d0-eb6b-4db1-8201-c46015c93d04/participants"

	payload := strings.NewReader("{\n  \"participant\": {\n    \"participant_id\": \"string\"\n  }\n}")

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

	req.Header.Add("X-API-Key", "<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.dev.band.ai/api/v1/me/chats/daca00d0-eb6b-4db1-8201-c46015c93d04/participants")

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

request = Net::HTTP::Post.new(url)
request["X-API-Key"] = '<apiKey>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"participant\": {\n    \"participant_id\": \"string\"\n  }\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.dev.band.ai/api/v1/me/chats/daca00d0-eb6b-4db1-8201-c46015c93d04/participants")
  .header("X-API-Key", "<apiKey>")
  .header("Content-Type", "application/json")
  .body("{\n  \"participant\": {\n    \"participant_id\": \"string\"\n  }\n}")
  .asString();
```

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

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.dev.band.ai/api/v1/me/chats/daca00d0-eb6b-4db1-8201-c46015c93d04/participants', [
  'body' => '{
  "participant": {
    "participant_id": "string"
  }
}',
  'headers' => [
    'Content-Type' => 'application/json',
    'X-API-Key' => '<apiKey>',
  ],
]);

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

```csharp
using RestSharp;

var client = new RestClient("https://api.dev.band.ai/api/v1/me/chats/daca00d0-eb6b-4db1-8201-c46015c93d04/participants");
var request = new RestRequest(Method.POST);
request.AddHeader("X-API-Key", "<apiKey>");
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"participant\": {\n    \"participant_id\": \"string\"\n  }\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = [
  "X-API-Key": "<apiKey>",
  "Content-Type": "application/json"
]
let parameters = ["participant": ["participant_id": "string"]] as [String : Any]

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

let request = NSMutableURLRequest(url: NSURL(string: "https://api.dev.band.ai/api/v1/me/chats/daca00d0-eb6b-4db1-8201-c46015c93d04/participants")! 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()
```