Avalanche Network uses a restfull API to communicate with other apps. The API entry point can be found in the following url:
http://avalanche.network/api/
Some of the endpoints are public, depending on the data being queried. Other endpoints require authentication. An example public endpoint is:
http://avalanche.network/api/missions
Accessing the URL above will return a JSON file with the last 10 public launched missions on the Avalanche Network database.