The GraphHopper Directions API uses open source projects under the hood from GraphHopper GmbH, komoot GmbH, OpenStreetMap and many more, often under the Apache License 2.0. For example, jsprit or the routing engine, that themselves uses other open source components.
Our entire infrastructure is built on top of open source using Debian linux, Ansible, nginx, bash, python, git, Java and many more open source projects. Without them our services would not be possible. Thanks a lot!