curl --request POST \
  --url https://your-instance.example.com/api/{session}/messages/seen \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "chatId": "1234567890@s.whatsapp.net",
  "messageId": "ABCDEF1234567890"
}
'

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({chatId: '1234567890@s.whatsapp.net', messageId: 'ABCDEF1234567890'})
};

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

import requests

url = "https://your-instance.example.com/api/{session}/messages/seen"

payload = {
    "chatId": "1234567890@s.whatsapp.net",
    "messageId": "ABCDEF1234567890"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

package main

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

func main() {

	url := "https://your-instance.example.com/api/{session}/messages/seen"

	payload := strings.NewReader("{\n  \"chatId\": \"1234567890@s.whatsapp.net\",\n  \"messageId\": \"ABCDEF1234567890\"\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))

}

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://your-instance.example.com/api/{session}/messages/seen",
  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([
    'chatId' => '1234567890@s.whatsapp.net',
    'messageId' => 'ABCDEF1234567890'
  ]),
  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;
}

{
  "message": "<string>",
  "success": true
}

{
  "docs": "https://docs.polymorfa.com/api/messages/send",
  "error": "missing required field: chatId"
}

{
  "error": "missing or invalid API key"
}

{
  "error": "internal server error"
}

{
  "docs": "<string>",
  "error": "<string>"
}