Thanks for making this!

For testing, I don't want to have to switch between generating a unique URL GUID and my tool...I'd rather have it be static.
Something like:

http://127.0.0.1:4430/11111111-2222-3333-4444-555555555555 will always be accepted by webhook-tester.

Maybe it could be a CLI switch like --static-guid 11111111-2222-3333-4444-555555555555?