Hello!
The “invalid signature” error when verifying the monday.get(‘sessionToken’) on your backend likely means the secret key used in jwt.verify doesn’t exactly match your Monday app’s Client Secret from the Developer Portal. Double-check this Client Secret for any typos or differences. Also, ensure you’re sending the raw token data from your React frontend without modification. Logging the token on both ends can help confirm it’s being transmitted correctly. Verifying the token with just the token and the Client Secret in a simplified backend test is a good next step. An incorrect Client Secret is the most probable cause.