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Free Software vs. Open Source


There is often some confusion about the terms “free software” and “open source”. The following is an attempt to provide a brief and concise differentiation. The philosophy of “free software” originated with Richard Stallman [0]. “Free” does not refer to “free as in free beer”, but to “free as in freedom”. “Open source” and “free software” are fundamentally different approaches [1].
“Free” in “free software” refers to four freedoms:

  • The freedom to run the program as you wish, for any purpose (freedom 0).
  • The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.
  • The freedom to redistribute copies so you can help others (freedom 2).
  • The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.

What is free software? - GNU Project - Free Software Foundation

Another important point of the philosophy of “free software” according to the Free Software Foundation (FSF) is that it should not be allowed to redistribute the program with a proprietary license in the context of Freedom 3. This is called copyleft: It guarantees that the “freedom” remains. However, the copyleft guarantee is not mandatory for the classification of software as “free software”: “We believe there are important reasons why it is better to use copyleft. However, noncopylefted free software is ethical too.” [2]

The practical guidelines of the “free software” movement can be found in a similar, somewhat more lax manner in the official Open Source Initiative (OSI).
But this consensus is only at the level of practical guidelines! The theories behind do not match.

The goal of the “free software” philosophy is social, ethical. Efficiency, quality, financial gain are side effects.
For the OSI, however, freedom is not the main focus. The OSI is primarily interested in:

[…] development method for software that harnesses the power of distributed peer review and transparency of process. The promise of open source is higher quality, better reliability, greater flexibility, lower cost, and an end to predatory vendor lock-in. [3]

About the Open Source Initiative | Open Source Initiative

“Freedom” in the spirit of “free software”, social and ethical improvements are side effects here.

Finally, the term “open source” does not even have to refer to the OSI. Frequently, “open source” only means what is manifestly arising from the name: the possibility of being allowed to read the source code. This does not imply the four freedoms the FSF considered to be central and is far from his ideas. This view of “open source” does not even agree with the OSI regarding the practical requirements.

[0] Richard Stallman may have started the free software movement. Nowadays, however, the idea of “free software” is carried by many individuals and organizations.
[1] Why Open Source Misses the Point of Free Software - GNU Project - Free Software Foundation
[2] What is free software? - GNU Project - Free Software Foundation