Paymo service uses the REST request format. REST is the simplest request format to use - it's a simple HTTP GET or POST action.
An example of a request URL:
http://api.paymo.biz/service/paymo.projects.getInfo?api_key=9c77f2cd64ec153b7364026af2ae87cc
&auth_token=aff3eb0b9a1f2963f808b44864cbdf5c&format=json&project_id=7801