If you need to validate a WebHook endpoint for Azure Event Grid, you have at least two options:
- Implement validation method in your application, which you will be calling using WebHook.
- Run standalone validator for a moment and then run your application on the same address.
The first option can be expensive or impossible (for example if you are going to use some SaaS tool in the subdomain you own).
The second option is quick and cheap. I created a sample Python web server, which only purpose is to respond to Azure Event Grid WebHook validation request.
Feel free to use, contribute and share: https://github.com/smereczynski/Azure-EventGrid-WebHook-Validator