Blender is licensed under the GNU General Public License (GPL), and the terms that matter to an organisation depend on whether it only uses the software or also distributes it. The Blender Foundation states that the GPL gives everyone the freedoms to use Blender for any purpose, to distribute it, to study and change it, and to distribute changed versions, and that the licence “strictly aims at protecting these freedoms” by requiring everyone to share their modifications when they also share the software in public.[1] This article follows the Foundation’s own statements and the licence texts it ships in its source repository. Interpretation beyond those documents is left to qualified counsel, and the Foundation says the same about its website pages.[2]
Which GPL version applies
Blender’s documents describe three layers. The licence page says the source code developed at blender.org is licensed by default as GNU GPL version 2 or later, that some modules use more permissive licences (the Cycles render engine is Apache 2.0), and that Blender also uses libraries from other projects: Python under the Python License, Bullet under the Zlib License, Libmv under the MIT License and OSL under a BSD licence.[1] It then says all the components together are compatible under GPL version 3 or later, and that this is the licence to use for any distribution of Blender binaries.[1] The repository README says Blender as a whole is licensed under GPL version 3 and individual files may have a different but compatible licence.[3] The source tree maps SPDX identifiers such as GPL-2.0-or-later, GPL-3.0-or-later, Apache-2.0, BSD-2-Clause, BSD-3-Clause, MIT, Zlib, MPL-2.0 and LGPL-2.1-or-later to licence texts in its doc/license folder.[5] The licence texts themselves permit a recipient to follow either the stated version or any later version when a programme says “any later version”, which is the mechanism that lets the version 2 or later source be combined into a version 3 binary.[6]
The COPYING file in the repository adds that, apart from the GNU GPL, Blender is not available under other licences.[4] Historically the Foundation reserved the right to offer a separate Blender License (BL) for revenue purposes. The BL text states that this dual-licence model was never activated and that the offer was cancelled for an indefinite period in June 2005.[8] For asset management purposes this means there is no commercial licence to buy that would relieve the GPL conditions.
Using Blender
Running Blender carries no obligation under the licence. The GPL text shipped with Blender states that activities other than copying, distribution and modification are outside the licence, that the act of running the program is not restricted, and that the output from the program is covered only if its contents constitute a work based on the program.[6] The version 3 text likewise affirms unlimited permission to run the unmodified program.[7] The FAQ confirms that Blender may be used commercially, that an organisation may give any official version to co-workers or share it internally on a server, and that the software can be downloaded free of charge.[2] There is no activation or registration: the licence page says no registration is needed and no internet connection is made when Blender is installed and used.[1]
Modifying Blender inside an organisation
An organisation that modifies Blender for its own staff has no publication duty. The FAQ states that the GPL allows an organisation to use a modified version of Blender internally without offering the source code, as long as it does not distribute it outside the company or organisation, and that the same applies to giving a changed version to co-workers or employees.[2] The Foundation frames this as a business model: companies can treat Blender as in-house software in the same way as large film studios.[2] The boundary is the organisation. When the changed version is shared with others outside the company, the FAQ says all the source code must be made available to them as GNU GPL.[2] Whether a contractor, subsidiary or customer counts as outside the organisation is a question the Foundation’s documents do not answer, and the GPL text should be consulted for the meaning of distribution.
Distributing Blender
Distribution triggers the licence conditions. The FAQ says anyone distributing Blender itself must follow the GPL rules, which means making the sources available, but that for official releases it is sufficient to provide information that forwards to the sources at blender.org.[2] For modified or self-built copies, the GPL text sets the mechanics. Version 2 requires that a work containing or derived from the program be licensed as a whole at no charge to all third parties under the licence, and requires that a binary be accompanied either by the complete corresponding source, by a written offer valid for at least three years to supply it, or by the offer information the distributor itself received.[6] Version 3 requires the entire work to be licensed as a whole under the licence when a modified version is conveyed.[7] Both versions state that rights terminate automatically if the licence is breached, while parties who have received copies from the breaching party keep their rights as long as they comply.[6]
The Foundation’s manual summarises the responsibilities in similar terms: provide a copy of the GPL with the program, include or make the source code available, license modifications under the GPL or a compatible licence, and do not restrict the program’s licensing beyond the GPL.[9] Redistributors who bundle Blender into a larger package must also keep track of the licences of the bundled libraries, which the licence page lists by name.[1]
Selling and rebranding
Selling is permitted. The FAQ states that a person can sell their own version of Blender, but only if they provide that version and its sources to their clients under the same GNU GPL, so that the client has all rights the GPL offers, including redistribution. It adds that this gives a basis for contracting and support businesses, and that code can be sold as fixed or changed code as long as it is delivered as GPL, without any duty to publish it for everyone.[2]
Rebranding is also permitted within limits. The FAQ says a redistributor is free to name Blender whatever they like and to repackage it under their own branding, provided it is delivered under the GPL conditions, but may not change Blender’s copyright notices or claim to have written it, and may not change existing claims or credits published for Blender, such as feature lists, galleries, release notes or reviews, without permission.[2] The trademark policy separately requires forks to be renamed, and that is covered in the trademark article.
Third-party components and screenshots
Because Blender includes libraries under other licences, a redistributor who ships a build inherits those notices. The source tree ships the Apache 2.0, BSD, Boost, MIT, MPL 2.0, Zlib and LGPL texts alongside the two GPL texts.[5] For documentation, the FAQ says that screenshots of the interface as a whole may be licensed as an author wishes, but individual items such as icons remain GPL, and that the splash screen and icons are GPL material.[2]
Compliance process
The Foundation describes how it handles reported violations. It will always first start a conversation to investigate, establish the facts and look for a mutually agreeable solution. Only when that is not possible, and only when its board considers that its mission is severely in danger, will it seek legal counsel and give a reasonable cure period.[1] It also offers feedback on licence compliance and best practices to organisations committed to adopting Blender as part of their IT infrastructure.[1] That commitment is a statement of practice, not a contractual term, and it does not limit the rights of other copyright holders whose code is in Blender, since the FAQ notes that developers keep their own copyright on the code they contribute.[2]
Out of scope
This article does not cover Python scripts and add-ons, which have their own rules in the add-ons article, the Blender name and logo, files produced with Blender, or the Foundation’s funding programs. It does not analyse copyright law in any country, and it does not describe third-party builds of Blender, such as those packaged by operating-system distributors, which are not Blender Foundation documents.