Which software movement is against proprietary software?

The Free Software Foundation (FSF) is an organization that advocates for the freedom to use, study, share, and modify software. The FSF is particularly known for its strong stance against proprietary software, which restricts user freedoms. The movement it represents promotes the idea that software should be free—not just in terms of cost, but also in terms of the liberties it provides to the users. This emphasis on the importance of freedom is fundamental to the philosophy of free software, highlighting issues such as user autonomy and community collaboration.

While other groups, like the Open Source Software Foundation (OSF) and the GNU project, also have important roles in the software community, they may not emphasize the ethical issues surrounding proprietary software to the same extent as the FSF. The term OSS refers to open-source software, which allows for access to source code and modification but may not always align with the full philosophy of freedom that the FSF upholds. Thus, the FSF stands out as the movement most closely associated with the advocacy against proprietary software.