Moodle lives from contributions, but the main core is mainly maintained by Moodle HQ. For all interested people, on this page (https://moodle.org/dev/contributions.php?version=x.x.x) you can see all developers that have ever contributed to this gorgeous project.
Moodle is a learning platform designed to provide educators, administrators and learners with a single robust, secure and integrated system to create personalised learning environments.