curl --request POST \
  --url https://your-instance.example.com/api/conversation/{conversationId}/send-message \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data @- <<EOF
{
  "body": "Thanks for confirming, we'll follow up tomorrow.",
  "attachments": [
    {
      "url": "https://r2.example.com/messages/.../quote.pdf",
      "filename": "quote.pdf",
      "contentType": "application/pdf"
    }
  ],
  "isInternal": false
}
EOF

import requests

url = "https://your-instance.example.com/api/conversation/{conversationId}/send-message"

payload = {
    "body": "Thanks for confirming, we'll follow up tomorrow.",
    "attachments": [
        {
            "url": "https://r2.example.com/messages/.../quote.pdf",
            "filename": "quote.pdf",
            "contentType": "application/pdf"
        }
    ],
    "isInternal": False
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    body: JSON.stringify('Thanks for confirming, we\'ll follow up tomorrow.'),
    attachments: [
      {
        url: 'https://r2.example.com/messages/.../quote.pdf',
        filename: 'quote.pdf',
        contentType: 'application/pdf'
      }
    ],
    isInternal: false
  })
};

fetch('https://your-instance.example.com/api/conversation/{conversationId}/send-message', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://your-instance.example.com/api/conversation/{conversationId}/send-message",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'body' => 'Thanks for confirming, we\'ll follow up tomorrow.',
    'attachments' => [
        [
                'url' => 'https://r2.example.com/messages/.../quote.pdf',
                'filename' => 'quote.pdf',
                'contentType' => 'application/pdf'
        ]
    ],
    'isInternal' => false
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://your-instance.example.com/api/conversation/{conversationId}/send-message"

	payload := strings.NewReader("{\n  \"body\": \"Thanks for confirming, we'll follow up tomorrow.\",\n  \"attachments\": [\n    {\n      \"url\": \"https://r2.example.com/messages/.../quote.pdf\",\n      \"filename\": \"quote.pdf\",\n      \"contentType\": \"application/pdf\"\n    }\n  ],\n  \"isInternal\": false\n}")

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

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://your-instance.example.com/api/conversation/{conversationId}/send-message")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"body\": \"Thanks for confirming, we'll follow up tomorrow.\",\n  \"attachments\": [\n    {\n      \"url\": \"https://r2.example.com/messages/.../quote.pdf\",\n      \"filename\": \"quote.pdf\",\n      \"contentType\": \"application/pdf\"\n    }\n  ],\n  \"isInternal\": false\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://your-instance.example.com/api/conversation/{conversationId}/send-message")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"body\": \"Thanks for confirming, we'll follow up tomorrow.\",\n  \"attachments\": [\n    {\n      \"url\": \"https://r2.example.com/messages/.../quote.pdf\",\n      \"filename\": \"quote.pdf\",\n      \"contentType\": \"application/pdf\"\n    }\n  ],\n  \"isInternal\": false\n}"

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

{
  "success": true,
  "message": {
    "_id": "67e0a0b0c0d0e0f0a0b0c0d1",
    "body": "Thanks for confirming, we'll follow up tomorrow.",
    "direction": "outbound",
    "senderType": "HUMAN",
    "createdAt": "2026-05-18T14:15:00.000Z"
  }
}

{
  "error": "Attachment not found",
  "message": "Attachment not found"
}

{
  "error": "Attachment not found",
  "message": "Attachment not found"
}

{
  "error": "Attachment not found",
  "message": "Attachment not found"
}