OpenAtlas uses solely open source technology. It is and always will be free of charge and open source to guarantee continued usage.
The code is freely available on GitHub. Have a look at the list below for an overview of used technologies.

Python is an interpreted, high-level, general-purpose programming language.
Website: https://www.python.org
Licence: Python Software Foundation License

Flask is a micro web framework, written in Python, with the ability toscale up to complex applications.
Website: https://palletsprojects.com/p/flask/
Licence: BSD

PostgreSQL is a free and open source relational database management system.
Website: https://www.postgresql.org/
Licence: PostgreSQL License

PostGIS is a spatial database extender for PostgreSQL and adds support for geographic objects.
Website: https://postgis.net
Licence: GPL 2 or later

Bootstrap is a free and open source CSS framework.
Website: https://getbootstrap.com/
Licence: MIT

Leaflet is a open source JavaScript library used to build web mapping applications.
Website: https://leafletjs.com/
Licence: BSD-2-Clause

Jinja is a full-featured template engine for Python with full unicode support.
Website: https://palletsprojects.com/p/jinja/
Licence: BSD