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Open Source but not Free Software (or vice versa)

I recently was at talk were Stallman was the keynote speaker, and he stated he hated the term open software, because it was geared to confuse people.

Now, I have since then read on to understand his stance, but I am unable to draw a line where free software becomes open source, and which licenses can be considered in each group.

For example I know that GPL, LGPL are free software licenses, but they are also open source licenses as well.

Is there a pure open source license? like MIT license? or is it all shades of grey.

Can a line be drawn?


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    And don't forget the "free as-in-beer" software. Commented Aug 31, 2011 at 21:06
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    @FrustratedWithFormsDesigner - I find that term discriminating with regards to those who prefer wine ;)
    – Rook
    Commented Aug 31, 2011 at 21:40
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    Stallman has his own breed of FUD. Secondly, GPL and LGPL are viral licenses not free licenses. Commented Aug 31, 2011 at 22:09
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    @Rook -- while I have enjoyed the odd "Free Beer" on several occasions "Free Wine" is a much rarer experience which usually involves looking at god awful art while listening to people saying nothing at great length. Free and drinkable wine is rarer still. Commented Sep 1, 2011 at 1:45
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    @Jonathan. So you wanted to take someone else's work and sell it as your own. But you griped because the owner of the software said you could do this as long as you let other people use your code in the same way. You would naturally prefer a BSD license which would allow someone like microsoft or yourself to make small amendments to the code and sell it under a restrictive license and not even acknowledge the original authors. Commented Sep 2, 2011 at 2:29

10 Answers 10


Stallman's beef with the term "open source" primarily seems to be that it focuses solely on methodology without also carrying along the ethical stance of the FSF. Given this, my conclusion is that:

  • Open Source Software is a development model in which the source code is made available to users and they are allowed to examine and modify it for their own purposes. Redistribution is generally allowed, although there may be restrictions upon doing so.

  • Free Software is an ethical position which provides a reason for using an Open Source development model. Adherents of the Free Software ethos will not, as a rule, place restrictions on the redistribution of their Open Source code, with the exception of preventing others from making closed versions of it.

(Incidentally, I once posited this distinction on a mailing list frequented by Stallman. It was one of the few posts using the term "Open Source" which didn't raise any objections from him, although he didn't endorse it either.)


The largest difference between Open Source and Free Software is that Free Software provides The Four Freedoms, where Open Source software is generally taken to be a lesser-form of openness compared to Free Software because it does not guarantee the same freedoms as a Free Software license though still provides access to the source code, or includes additional restrictions on top of The Four Freedoms while still providing access to the source code.

Example, the JSON license is Open Source, but is not Free Software because it adds the additional restriction "The Software shall be used for Good, not Evil", while the GPL is Free Software because it does guarantee all of those freedoms and imposes no additional restrictions.

Drawing a line is easy. Does your license provide The Four Freedoms, and does it add additional restrictions on top of said Freedoms?

Yes,No= Free Software
No,Yes= Open Source
Yes,Yes=Open Source
No, No= Open Source

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    Also note that Free Software cannot be redistributed as non-free.
    – user1249
    Commented Sep 1, 2011 at 17:08
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    @ThorbjørnRavnAndersen: Nope; BSD is a perfectly good Free Software license, and is listed on the FSF's list as a Free Software license compatible with the GPL. You can redistribute it as non-Free. You can't redistribute copylefted software (the GPL being the archetypical copyleft license) as other than copylefted. Commented Sep 30, 2011 at 21:43

I'll consider that you talk about free licenses in the sense of the Free Software Foundation, and open source as advocated by the Open Source Initiative. (Note : Free software licences does NOT forbid charging for the distribution of a software)

The main difference is based on ethics : FSF value the conservation of freedom above everything else (freedom to modify and redistribute, but also assuring that freedom can't be withdrawn from users), whereas open source value the technical aspects of being able to look at the source code (because more people can review the source code, thus theoritically leading to better, more reliable software).

Thus all free software licenses are automatically open source licenses because they automatically allow you to have access to the source code, but it's not always true the other way (even if it often is).
For example, the NASA Open Source Agreement is approved by the OSI but not by the FSF.
Read Why Open Source misses the point of Free Software if you haven't already ; of course it's the FSF point of view and is biased, but I still find it interesting.


Open source software is, what its name says, software with source available to the public (or whoever).

Free software is software that is, in the most wide term, not commercial. Not sold.

Most of other things fall in between, with variations on the subject. And I'm not exactly a fan of Stallman, since he's one of the main guilty ones for making the confusion with his GPL and whatever licences.

In any case, rant aside, if you're interested in the subject and are willing to go a little deeper in it, there is a nice book by O'Reilly, Understanding Open Source and Free Software Licensing which deals with it in a gentle way.

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    Free Software can be sold for profit, and can be sold commercially, so long as you are providing The Four Freedoms outlined at [0]. Generally companies in these scenarios profit by providing support contracts. Free Software is software which provides The Four Freedoms, as outlined in the Free Software Definition, at [0] . [0] gnu.org/philosophy/free-sw.html Commented Sep 1, 2011 at 0:23
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    @Jeff Welling - Not according to my definition of free. And I think I already hinted what I think of Stallman and his definitions.
    – Rook
    Commented Sep 1, 2011 at 1:23
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    -1 for misrepresenting Stallman's roll in 'the confusion' (chronologically, the GPL/Free Software came first, Open Source was created after), but +1 for the link to the O'Reilly book hehe. Commented Sep 1, 2011 at 2:14
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    @Jeff: Chronologically, FLOSS (Free/Libre/Open Source Software) existed long before Stallman came along and invented the term "Free Software" - it was even the default once upon a time, so it didn't need a name until closed commercial software became the norm. Commented Sep 1, 2011 at 9:05
  • @Jeff - I'm quite certain he didn't invent the term "free" nor "open source" ;)
    – Rook
    Commented Sep 1, 2011 at 11:17

In the general case, there is no difference. 'Open Source' is a marketing term created to promote free software in the business world. The goal was to remove the ambiguity around the world 'free'.

Licenses which are Open Source Initiative approved

Licenses which are Free Software Foundation Approved


I strongly suggest you read http://www.fsf.org/about/, this explains the philosophy behind free software.

Open source simply means that the source code is available, technically, free software is open source; yet open source software does not have to be free.

And no I do not think there is a "pure open source" license. Open source meaning only having source available, has nothing to do with licensing.

  • -1. Open Source does indeed have a clear and unambiguous definition from the Open Source Initiative, and means far more than simply having the code available.
    – TRiG
    Commented Aug 19, 2012 at 23:58

Stallman is proceeding from an ideological viewpoint. He is a proponent of copyleft, thus he sees things along that ideological divide (which will become clear when you read his writings). You may be confused by the term "free", which is why you'll see the phrases "free as in beer" or "free as in speech" distinctions. This collision in meanings happens because the English word "free" can mean "without cost" or "political freedom".

Think free as in free speech, not free beer.

Stallman wants you to think of "political freedom".

he hated the term open software, because it was geared to confuse people

Eliminating the term "open source" also means eliminating a competing organization (OSI) in favor of his preferred organization (FSF). By eliminating the competing vocabulary, you will only be able to "goodthink" - to think in terms of GPL. The "confusion" is that you are not using

which licenses can be considered in each group

Wikipedia has a good set of lists comparing and constrasting them.


In terms of software and licenses, they are the same thing.

Open Source was coined as a new term for free software because the word "free" was scary to businesses.

The GNU Project has strongly emphasized the term free software, as they feel the focus on freedom is most important. But, as the succinctly state, "The Free Software movement and the Open Source movement are like two political camps within the free software community."


Another way of looking at it is that the software is free, however, various "open source" licensing agreements restrict how you can modify and re-distribute the code.


Lines can be drawn:

  • Public domain. This is completely open.

  • Free to use and modify and sell but must retain author's name internally. (BSD-ware)

    • Optional clause: Must not advertise that it contains content made by the author. (Since the author didn't oversee the modifications, the author isn't associated with the final product.)
  • Free to use and modify and sell but must redistribute the original material. (GNU-ware) GNU is not free; it is viral and infects anything it touches with it's own license restrictions.

  • Free to use for a limited time and share with others, but not modifiable. (Share-ware)

  • Free to use but not modifiable. (Free-ware)

  • Pay to license source code and modifiable. (Commercial open source)

    • Several Operating Systems are distributed like this for example, because it is too difficult to distribute a binary of an operating system which can link with custom software. ThreadX RTOS, Nucleus RTOS come to mind.
  • Pay to use but not modifiable. (Commercial-ware)

  • Pay to use and extendable but not modifiable. (Commercial-ware with third-party plugins)

  • Just curious, is there a pay and modifiable model?
    – aggietech
    Commented Aug 31, 2011 at 22:35
  • They're called Plugins. Commented Aug 31, 2011 at 23:12
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    What OP means by 'GNU is not free' is that the GPL guarantees that nobody can take away the freedom provided by the GPL, not even if they improve on your program and release under a different license. Commented Sep 1, 2011 at 0:30
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    -1 for echoing the "Viral" FUD. Its a falsehood propagated by companies that sell software (some of which really does have viral terms and conditions). Commented Sep 1, 2011 at 1:49
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    @aggietech. Yes! Its not as common as it used to be. IBMs mainframe operating systems used to be delivered as source code which you could modify in any way you pleased. Its still reasonably common for local government software. This is because some jurisdictions require the auditors have access to all source code. Commented Sep 1, 2011 at 1:54

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