monday-webhooks

monday.com Webhooks

When to Use This Skill

• Setting up monday.com webhook handlers
• Implementing the challenge handshake required at registration
• Debugging JWT (Authorization header) verification failures
• Understanding monday.com event types and the event payload wrapper
• Handling board, column, subitem, and update events

Two things every monday.com endpoint must do

monday.com webhooks are unusual — there are two separate checks, not one:

1. Challenge handshake (required). When a webhook is created, monday.com POSTs { "challenge": "<token>" }. Your endpoint must echo it back as { "challenge": "<token>" } or registration fails. This is the only check guaranteed for every webhook, including no-code and personal-token webhooks.
2. JWT verification (when present). For webhooks created by an integration app, monday.com signs each request with a JWT in the Authorization header (HS256), signed with your app's Signing Secret. Verify it with a JWT library. Webhooks created with a personal API token or the no-code board integration may not send this header.

monday.com does not follow the Standard Webhooks spec, and the JWT is not an HMAC over the request body — it is a self-contained token that authenticates the sender. Because verification never reads the body, parsing JSON before verifying is safe here (unlike Stripe/GitHub HMAC schemes).

Verification (core)

import { jwtVerify } from 'jose';

// monday.com signs each request with a JWT in the Authorization header (HS256),
// signed with your app's Signing Secret (board webhooks) or Client Secret
// (app lifecycle webhooks). jwtVerify throws on a bad signature or expiry.
async function verifyMondayJwt(authHeader, secret) {
  if (!authHeader) throw new Error('Missing Authorization header');
  const token = authHeader.startsWith('Bearer ')
    ? authHeader.slice(7)
    : authHeader;                              // monday sends the raw token
  const { payload } = await jwtVerify(
    token,
    new TextEncoder().encode(secret),
    { algorithms: ['HS256'] }
  );
  return payload; // { accountId, userId, aud, exp, iat, ... }
}

// On registration monday POSTs { "challenge": "<token>" } — echo it back first:
//   if (body.challenge) return res.status(200).json({ challenge: body.challenge });