The terms open-source software and free software are often used interchangeably, but they come from different philosophies. Both support users’ ability to access and modify software under appropriate licenses, yet they emphasize different reasons for making software available.

Understanding open source vs free software helps users, developers, and businesses understand what software licenses permit—and why the distinction matters beyond price.

What Is Open-Source Software?

Open-source software is software distributed under a license that meets the Open Source Definition, maintained by the Open Source Initiative (OSI).

This means more than simply making source code visible. The license must allow activities such as using the software for different purposes, studying its code, modifying it, and redistributing the original or modified versions under specified conditions.

Open-source software can be developed by individuals, communities, nonprofit organizations, or businesses. Companies can also sell open-source software or charge for related services, support, and hosting.

Examples include the Linux kernel, the Firefox browser, and the Apache HTTP Server.

What Is Free Software?

Free software is defined by the Free Software Foundation (FSF) in terms of users’ freedom and control over their computing.

The word free refers to liberty, not necessarily price. The FSF identifies four essential freedoms:

• Run: Use the program for any purpose.
• Study: Examine how it works and access the source code needed to do so.
• Redistribute: Share copies with others.
• Improve: Modify the software and distribute modified versions.

These freedoms allow users to adapt software to their needs instead of depending entirely on the original developer.

Free software does not have to be given away at no cost. Users and businesses can pay for copies, development, support, or distribution, provided the software’s license preserves the required freedoms.

Open Source vs Free Software: What’s the Difference?

The main difference is the emphasis behind each term.

These are differences in emphasis, not necessarily in the software itself. In practice, the two categories largely overlap: licenses that qualify as open source generally also qualify as free software under the FSF’s definitions.

For example, the GNU General Public License (GPL) and the Apache License are recognized as both open-source and free-software licenses, although their conditions differ.

Why Do the Terms Matter?

The distinction helps explain why people choose and evaluate software differently.

Developers may favor open-source projects because they can inspect code, collaborate with contributors, and build on existing work. Free-software advocates place particular importance on whether users retain the freedom to run, study, modify, and share programs.

For businesses, the practical questions include licensing obligations, maintenance, security, compatibility, and support. A license may permit commercial use while still imposing conditions on redistribution or modified versions.

Neither label automatically guarantees that software is secure, well maintained, easy to use, or completely free of charge. Users should review the actual license and the project’s maintenance practices before adopting it.

Conclusion

Open source vs free software is primarily a distinction between philosophies: open source often highlights collaborative development and practical benefits, while free software centers on users’ freedoms.

The two approaches share substantial common ground, and many projects satisfy both definitions. Whether you are choosing software for personal use or building a commercial product, check the license to understand your rights and responsibilities rather than judging by the label alone.