Creating API apps

My church wants to make apps for an online community called the Table Project. ([login to view URL]) Apps that fit the needs of our church such as a book meeting room app and whatever we need as a community. The apps can be developed in any language. The only point of contact the app has is with a system called a REST API. These apps would be used not only by us but other chuches all over the country and you'd be a contact for other churches and this organization as a possible app creator.