The Insight Software Consortium reaffirms the Open Software Initiative's Open Source Definition

Earlier this year, the concept of open-source software was challenged by software that was being licensed under very specific clauses that brought controversy to the open-source software community.

Following this controversy, the Open Software Initiative made a public call to organizations to sign a public affirmation of its role in maintaining and stewarding the Open Source Definition.

The Open Software Initiative (OSI) is a non-profit organization dedicated to promoting open-source software since 1998. The organization has been instrumental in combatting legal terms and clauses in licenses that may be detrimental to the open-source ecosystem. The OSI promotes understanding of the true meaning of open-source software.

The Insight Software Consortium board unanimously voted to support the Open Software Initiative’s unequivocal stance of the Open Source Definition in its last meeting.

The Insight Software Consortium expressly supports the Open Software Initiative’s public affirmation.

The Insight Software Consortium encourages all of its software ecosystem to be licensed under the Apache 2.0 or similar OSI-approved licenses. The Insight Toolkit (ITK) is licensed under an Apache 2.0 license.


I was curious about this “software that was being licensed under very specific clauses that brought controversy to the open-source software community.”

So that other readers of this topic do not have to dig as deeply as I did: this is referring primarily to MongoDB’s recent relicensing under their newly crafted Server Side Public License (SSPL), intended to serve the same goals as the GNU Affero Public License, but more effectively preventing big cloud companies from leveraging OSS on their Software-as-a-Service platforms “without giving back.” MongoDB has submitted the SSPL to the OSI for consideration as an open-source license, but there are a lot of concerns, so it’s not looking likely that it will be accepted.

This is a contentious topic and I think it’s critical that we as a community understand the perspectives and arguments going on before jumping to any strong position. Here is a very nice thread on the Open Source StackExchange site going into detail about the SSPL, and what the OSI’s concerns are about it:

In my view, this debate highlights a big advantage of permissively licensed software like ITK: greatly reduced legal complexity, and unambiguous freedom to use the software as you see fit, regardless of commercial gain.


Thanks for the follow-up and pointers @ctrueden :+1:, great points.

Yes, the MongoDB re-licensing as SSPL spurred the need to remind ourselves of the true definition of open source. Re-licensing to non-OSI-approved licensing has happened in the past is trending again. For example, CockroachDB recently changed their license to a non-OSI approved license that adds additional restrictions.


Open source means more than the ability to see the code. The Open Source Definition empowers us to, e.g.:

  • Fix issues.
  • Develop new methods.
  • Build on the software to provide value and make a living.

The value from open source comes from these freedoms and community-driven development.

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