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I love creating games, and I've always made games using OpenGL and not with game engines such as Unity or Unreal. Can I legally sell the games I made with OpenGL?

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    \$\begingroup\$ What makes you believe that you could not sell games made with OpenGL? What information have you gathered up to now that would help you answer your question? \$\endgroup\$ – Vaillancourt Jun 20 '18 at 21:10
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    \$\begingroup\$ www.opengl.org/about/ : "End users, independent software vendors, and others writing code based on the OpenGL API are free from licensing requirements" \$\endgroup\$ – Jimmy Jun 20 '18 at 21:39
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    \$\begingroup\$ not a lawyer so I just want a simple answer We're not lawyers either. In any case, you should hire a lawyer for law related issues before releasing a game. \$\endgroup\$ – Vaillancourt Jun 21 '18 at 2:27
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    \$\begingroup\$ A common misunderstanding; the "open" in "OpenGL" actually has nothing to do with open-source software, and OpenGL pre-dates the open-source movement and usage of that term. It refers to OpenGL's status as a standard, \$\endgroup\$ – Maximus Minimus Jun 21 '18 at 4:51
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    \$\begingroup\$ Not only has the “Open” in OpenGL nothing to do with open source, also open source / free software has nothing to do with being unable to sell it. Only it gets a bit more tricky to convince custumers to actually buy the software, when not only they can easily copy it from elsewhere but even do so legally. \$\endgroup\$ – leftaroundabout Jun 21 '18 at 14:19
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Yes, you can sell OpenGL-rendered games.

The specifics depend on the library you're using. I'll get back to that.

First: OpenGL is an open standard and related API-set that establishes the protocol for communication between your application and video card / GPU. Typically this communication protocol is implemented by means of an operating system driver, and a supporting library which gets shipped with your game. OpenGL is fairly ubiquitous: Linux, Mac, Windows, iOS, and Android all typically have it pre-installed in the system. Loads of things you buy and that people sell are rendered using OpenGL.

It's the people making the operating systems and GPUs that have to worry about OpenGL licensing. OpenGL clarifies in its About section on Licensing that “End users, independent software vendors, and others writing code based on the OpenGL API are free from licensing requirements.” (That's you.)

(Thanks Jimmy for pointing out the About section.)

The library's license is what matters.

There's probably a library you're using to render via OpenGL though. It might be GLFW, freeglut, Allegro, SDL, SFML, Ogre3D, or others. Your library's license has more relevance here because your program has to ship with the library and the license will control how you can do that.

If you're not actually using any library at all, you have no licensing expectations in this area.

If you are, fortunately all the OpenGL libraries I know of are fine with this:

  • All the ones I just mentioned use the zlib license.
  • Except for Freeglut and Ogre3D, which use the MIT license (the X Consortium variant in Freeglut's case).
  • Older versions of Ogre3D (before 1.6) used Gnu LGPL.
  • Older versions of Allegro used a giftware license (summarily “do whatever you want with it”).

Check the license for the exact version of the libraries you're using to know what your obligations are.

You'd have some problems if you used Gnu GPL (as opposed to LGPL) licensed libraries, since that can bind you to redistribute your software's source code. There may also be issues if the library required royalties but this is also not the case. (You could still sell your game, you'd just be obligated to fork some of the profit elsewhere.)

The specific license involved may bind you to give attribution to the library, or to ship the library's license with your source code, so check the license and see what it instructs you to do. Usually people have buried in their app somewhere an "About" section that contains a "Boring legal stuff" link which itself is just a long scrolling textbox full of all the licenses they have to reproduce, and usually that is enough. Consult your library's license.

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    \$\begingroup\$ The Allegro license was formerly a "giftware" license that allowed you to do whatever you wanted with it. It has since changed to a MIT license. Allegro License Ogre3D was an LGPL license that changed recently to MIT as well. \$\endgroup\$ – Blerg Jun 21 '18 at 5:24
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    \$\begingroup\$ You don't necessarily have to use OpenGL through another library. \$\endgroup\$ – Reinstate Monica Jun 21 '18 at 7:57
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    \$\begingroup\$ A real world example is Google Chrome's chrome://credits/ page, which has all libraries used listed there, with their licenses. \$\endgroup\$ – Ismael Miguel Jun 21 '18 at 8:35
  • \$\begingroup\$ @Blerg Thank you for that, I must have gotten something mixed up while checking licenses. I've updated the post. \$\endgroup\$ – doppelgreener Jun 21 '18 at 8:48
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    \$\begingroup\$ @Cubic Is there some phrasing you'd recommend? Earlier in that post I already introduced these libraries as “a library you're using to render via OpenGL” and I'm still talking about those at the point I say “OpenGL libraries”, which is intended as a shorthand reference that I was hoping was clear in context. If that's inadvisable though, is there something you'd suggest I say there instead? \$\endgroup\$ – doppelgreener Jun 21 '18 at 10:19

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