Open Source Publishing (OSP) is a Brussels-based design collective founded in 2006 as part of the art organization Constant. The group is committed to exploring the creative potential of design through the exclusive use of Free and Open Source Software (F/LOSS), working across disciplines such as graphic design, typography, cartography, and illustration.

Rather than operating as a traditional studio with a singular founder, OSP functions as a collaborative collective. Among its early and influential members are Pierre Huyghebaert, known for his involvement in experimental and collaborative design practices, along with Alexandre Leray, Ludivine Loiseau, and Stéphanie Vilayphiou—each of whom has played a key role in shaping the collective's direction through workshops and creative initiatives.

OSP is known for several notable projects, including Relearn, a summer school that fosters collective learning in design using F/LOSS tools. The group is also a regular participant in the Libre Graphics Meeting, an international gathering of developers and users of open-source graphics software. Additionally, OSP has contributed to the Caveat Research Project, which investigates collaborative models and working conditions within the arts and design sectors.