Blender addon license is understood to be de facto GPL

[julien-haven]

BlenderTools

• Addon: All blender addons
• Question: As per the blender license terms, all blender addons that make use of the blender python API are de-facto considered GPL. Would you mind editing the license of the Epic addons to clarify this ? The license terms about blender addons can be found here https://www.blender.org/about/license/

[lunathir]

It has to be compatible with GPLv2-or-later, not necessarily have to be GPLv2-or-later. MIT license is compatible with GPL, and actually is more permissive than GPL.

[julien-haven]

The update to MIT license is posterior to this question being asked, as it was previously released under the Unreal Engine EULA.
I also believe that MIT is compatible with the Blender license, so this issue has been answered !

[andylizi]

I'm not sure that interpretation is meaningful here. MIT being GPL-compatible only means that MIT code can be used together with GPL code. It does not mean the end result is not de facto GPL, as explained in this StackExchange answer: How are GPL-compatible licenses like MIT usable in GPL programs without being subject to the copyleft provision? - StackExchange

In addition, https://www.blender.org/about/license/ clearly states that:

Your customers will receive the script under the same license (GPL), with the same free conditions as everyone has for Blender.

https://code.blender.org/2019/06/blender-is-free-software/ :

Paying for an add-on can only mean access to the add-on download service… offering it to you as GNU GPL.

The wording here does not seem to leave much room for alternative interpretations.