Author of Dr. Geo, the GNU interactive geometry software. Initial developer of the Freeduc-cd project, contributor to the Pharo Smalltalk project.

Hilaire started the development of Dr. Geo in 1996. In 1998, he ported it to GNU/Linux at a time where no interactive geometry software existed on this system. It latter became officially a GNU application blessed by Richard Stallman. In the spirit of free software and access to source code, Dr. Geo integrated scripting and programmed figure as well as code introspection from the application itself in an interactive programming environment.

He initiated and developed Freeduc-cd, a live system to easily demonstrate the capabilities of the GNU system for education and teaching.