Here are some interesting projects to which we've been able to contribute, sometimes very lightly, sometimes thoroughfully:
GNOME is one of two main desktop environments for GNU/Linux (the other one being KDE). As with all other Free Software project, any contributor with required skills is welcome.
Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design.
Some Django projects from 2xlibre.net:
Moreover, 2xlibre.net is privileged to design and maintain internal management tools for the following organisations: Foyer Handicap (source code), Fondation Carrefour (source code), Croix-Rouge neuchâteloise (source code).
From end of June 2020, a new bill format is introduced in Switzerland (see paymentstandards.ch/en).
2xlibre.net created and maintains the Python qrbill package which allows to produce such bills. Moreover, a mini Web app based on this package is available on this site to allow everyone to freely produce Swiss QR bills.