Q:

Webhook URL verifications with a challenge

I want to validate Webhook URLs created by our clients to make sure they indeed have the ownership of the endpoints. One common practice is sending a "challenge" via a GET request to the potential endpoint, and the endpoint should quickly respond back with the "answer" - like https://docs.microsoft.com/en-us/linkedin/shared/api-guide/webhook-validation. 
The issue is some of our clients want to use Zapier as the webhook endpoints, and as far as I know, Zapier doesn't allow the customers to have that kind of validation workflow and respond back to the GET request caller. 
My question is how we should get around it for such integration platforms? Whitelist Zapier? Or some other forms of Webhook URLs validation? Is the validation nice to have or a necessity?  
Thanks!

A:

David here, from the Zapier Platform team. 
That's a great question! The short answer is that that's not currently possible, but it's a good feature request. 
If whitelisting Zapier is possible, that's a good route to take. 

Is the validation nice to have or a necessity?

Zapier has infinitely many webhook urls and gives no indicator that they're tied to an active Zap. So there's very little chance of someone using your url that isn't you. I would say that in this case, the verification isn't necessary. 

