Is there any idea to use a suitelet as web hook. But getting 405 method not allowed due to user agent

Would need more info to help out. But off the top of my head I know when working with NetSuite you need to set User Agent to Mozilla/5.0

Yes @Addison Regnier but i am not permitted to set any header in the web hook just i can submit the suitelet url.

When I had to do this in the past I used a lambda function to proxy the webhook and add the header

Thanks @michoel for your valuable comment. Will work for it