Magento is a highly extensable e-ecomerce framework with many moving parts. Just one such part is the SOAP or XML-RPC based API interface. Which allows 3rd party programs to access store content.
However, sometimes things fail. Mage Ape wants to help you troubleshoot.
Start by entering your domain.
example.com Mage Ape will assume defaults and test unauthenticated requests. You can also specify the full path to the WSDL.
If you specify the user and password, Mage Ape will start a session and try to pull some data from the store. If any step fails, Mage Ape dutifully prints the error message for you you see.