Ah, it's because your path in your API definition is wrong, your API is on http://localhost/test-api/
/get will proxy to ->
httpbin.org/get (If that is your target).
But you have added a route to a whitelist which is: http://0.0.0.0:5000/
Which, in proxy terms, would be:
http://localhost/test-api/http://0.0.0.0:5000/, which is totally invalid. And since it's a white-list, only that pattern will pass, so your request to
/get is not on the white list, so it will fail.
The path you put in the designer is for routes that are on your target. So for example, httpbin.org has:
So to white list those endpoints simply add
put as paths (with the methods GET, POST and PUT) and then those will be allowed through, but all others will fail.
Hope that clarifies things