What is it called? A form submission app that will send information to my WordPress as posts

I need to know what it is called, so that I can search for how to do it. (If you have a good starting point/tutorial/already exists and can be modified, please let me know.)

I want an program that I can install on desktop/mobile/tablet. It is a form. When submitted, the information goes to fill out the fields in my WordPress site's "New Post."

Thanks, Justin