As part of our software development training at CodeClan, I worked as part of a group of 4 to create a team project: An educational application written entirely in vanilla Javascript, and using one or more APIs.
We decided quickly that we wanted to use the Google Maps API, and from there had the idea to create an educational quiz using the map. To make the quiz more interactive for a user, we would allow them to choose their role; either the user could be a participant, and take one of the existing quizzes, learning about the world as they went along, or they could take the role of a quiz master, creating their own questions and answers for other users to take.
For a database, we used FireBase, a mobile development platform allowing each team member access to the same database, updated in real-time, as we collaborated on the project.