Recently Unreal Engine 4 become free with Royalty fees. What about the code? Is it opensource or no?


1 Answer 1


From their website

Full Source Code Access

With C++ source code for all of Unreal Engine 4, you can customize and extend Unreal Editor tools and Unreal Engine subsystems, including physics, audio, online, animation, rendering as well as Slate UI. With complete control over engine and gameplay code, you get everything so you can build anything.

This is not the same as open source however, and since you pay royalties instead of an upfront price it is unlikely that there is an open source license available.

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    \$\begingroup\$ By definition having access to the source code makes Unreal Engine 4 "open source." I think what you mean to say is that Unreal Engine 4 is not like most other open source projects that use popular licenses (GPL, Apache, MIT, etc.); Unreal Engine 4 is not copyleft, not "free as in freedom," nor even free in the monetary sense since you must still pay royalties to use. \$\endgroup\$ Feb 12, 2016 at 21:14
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    \$\begingroup\$ @VilhelmGray I'm going by the following definition: "Open-source software (OSS) is computer software with its source code made available with a license in which the copyright holder provides the rights to study, change, and distribute the software to anyone and for any purpose." Which seems to be the predominate definition of open source. The quote is from wikipedia btw. \$\endgroup\$ Feb 19, 2016 at 9:45
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    \$\begingroup\$ @VilhelmGray, the phrasing I use for situations like UE4 is "source-available". \$\endgroup\$
    – Mark
    Dec 9, 2016 at 0:19
  • \$\begingroup\$ @Mark Ah yes, "source-available" may be a more apt term for this situation; I believe Daniel Carlsson is correct that UE4's source distribution model does not match the predominate definition of "open-source" in use today. \$\endgroup\$ Dec 9, 2016 at 17:12

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