Send a WhatsApp Message with Node.js

Here's how to send a WhatsApp message from Node.js using the fetch function that's built into Node.js 18 and newer — no npm packages to install. You'll end up with a small module you can use from an Express or Next.js app, a background worker or a one-off script, to send text, images and documents and track delivery.

Check your version with node --version; you need 18 or newer.

Before you start

You need three things from your InstaMessage dashboard. It takes about five minutes:

1. A free account. Sign up here — no card needed.
2. A connected instance. Create an instance and scan its QR code with WhatsApp on your phone (Settings → Linked devices → Link a device), until its status shows Connected.
3. Your instance_id and access_token. On the instance's page, generate an API credential. The token is shown only once, so copy it somewhere safe straight away.

Keep both out of your code: store them as environment variables, so they never end up in Git. On macOS or Linux:

export INSTAMESSAGE_INSTANCE_ID="your-instance-id"
export INSTAMESSAGE_TOKEN="your-access-token"

On Windows (PowerShell):

$env:INSTAMESSAGE_INSTANCE_ID = "your-instance-id"
$env:INSTAMESSAGE_TOKEN = "your-access-token"

Step 1: Write a small module

Save this as instamessage.mjs. It adds your token to every request and throws an error with the API's own message when something goes wrong:

const API_URL = "https://www.instamessage.in/api/v1";
const INSTANCE_ID = process.env.INSTAMESSAGE_INSTANCE_ID;
const TOKEN = process.env.INSTAMESSAGE_TOKEN;

async function request(method, path, body) {
  const response = await fetch(API_URL + path, {
    method,
    headers: {
      Authorization: "Bearer " + TOKEN,
      "Content-Type": "application/json",
      Accept: "application/json",
    },
    body: body ? JSON.stringify(body) : undefined,
    // Media files are downloaded before sending, so allow up to 60 seconds.
    signal: AbortSignal.timeout(60_000),
  });

  const data = await response.json().catch(() => ({}));

  if (!response.ok || !data.success) {
    throw new Error(data.error ?? "Request failed with HTTP " + response.status);
  }

  return data;
}

// Send a WhatsApp message. Extra fields (type, media_url, file_name) are passed through.
export function sendMessage(to, message, extra = {}) {
  return request("POST", "/messages/send", { instance_id: INSTANCE_ID, to, message, ...extra });
}

// Look up a sent message, including its delivery status.
export async function getMessage(messageId) {
  const data = await request("GET", "/messages/" + encodeURIComponent(messageId));
  return data.message;
}

The .mjs ending lets you use import / export without changing your package.json.

Step 2: Send your first text message

Create send.mjs with your own WhatsApp number to test it:

import { sendMessage } from "./instamessage.mjs";

const result = await sendMessage("919876543210", "Hello from Node.js! 👋");
console.log("Sent! Message ID:", result.message_id);

node send.mjs

Within a second or two the message lands on the phone. result holds the API's reply, for example { success: true, message_id: "3EB0A1B2C3D4E5F6", sent_via: "device", fallback_status: null }.

Step 3: Handle errors

Use try / catch — the error message is the API's explanation, or the network problem:

import { sendMessage } from "./instamessage.mjs";

try {
  await sendMessage("919876543210", "Your OTP is 482913. It expires in 10 minutes.");
} catch (error) {
  console.error("WhatsApp message failed:", error.message);
}

What usually causes an error:

• HTTP 401 — the access token is missing, wrong or revoked.
• "Instance is not connected" — reconnect the instance from your dashboard.
• "instance_id does not match this token" — the token is for a different instance.
• "You've reached your plan's monthly message limit" — upgrade, or wait for the new month.
• HTTP 429 — more than 30 send requests in a minute; wait and try again.

Step 4: Send an image or a document

Pass a type and a public media_url as extra fields. The text becomes an optional caption:

import { sendMessage } from "./instamessage.mjs";

// An image with a caption (JPG, PNG or WebP, up to 5 MB)
await sendMessage("919876543210", "Just in: our new collection", {
  type: "image",
  media_url: "https://example.com/images/new-arrival.jpg",
});

// A PDF, with the file name the recipient will see
await sendMessage("919876543210", "Here is your invoice.", {
  type: "document",
  media_url: "https://example.com/invoices/42.pdf",
  file_name: "Invoice-42.pdf",
});

Videos, audio and voice notes work the same way — the media rules list every type and size limit.

Step 5: Check if it was delivered and read

import { getMessage, sendMessage } from "./instamessage.mjs";

const result = await sendMessage("919876543210", "Did you get this?");

const message = await getMessage(result.message_id);
console.log(message.status); // pending, sent, delivered, read or failed

read only appears when the recipient has read receipts turned on. To get delivery and read updates pushed to your server as they happen, set a webhook on your instance.

Next steps

• See every field, error and limit in the API documentation.
• Receive incoming messages with a webhook, and get delivery updates on your server.
• Compare plans and message limits.

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