The Multics License is a BSD-style permissive license covering the released Multics source. Keep the notices, and do not imply an endorsement.
On this page
What it does
The Multics License covers the source of Multics, the operating system whose ideas fed into Unix, released by its corporate owners and listed by the Open Source Initiative for archival reasons. It is BSD-style permissive. You may use, modify, and redistribute the code, including commercially and inside a closed product, as long as the copyright and permission notices stay with it. The one extra rule is the familiar one: you may not use the copyright holders' names to present them as endorsing your product.
Details
You will almost certainly never meet this license in a dependency tree. If you do, it behaves like BSD: host it, ship it, link it into closed code, publish nothing of your own. The reason to record it rather than wave it through is that a procurement reviewer reading your component list will not recognise the name either. An unexplained line in that list costs more of everyone's time than a stored license text and a one-sentence answer.
Pros
- Easy to drop into a closed, paid product. Procurement has seen this family hundreds of times.
- No copyleft on your own files. You keep your source private.
Cons
- The notice duty is easy to miss in a desktop, mobile, or container build. A web page is not a substitute for notices inside the artifact.
- Buyers who want an express patent grant will ask you to prefer Apache-2.0 over a short MIT-style text.
What it allows and requires
Choose a category to see the full grant in one scannable list. Permissions show what the license allows, limits show what it withholds, and obligations show the conditions your release process must satisfy.
Permissions
Commercial use
You may ship the code inside a paid product. The license does not restrict commercial use.
Modify
You may change the code, including keeping those changes private, unless a later obligation says otherwise.
Distribute
You may give copies to others. Distribution is what usually turns notice and source duties into real work.
Sublicense
You may include the code under your own product terms, so long as you still meet this license's conditions.
Private use
Use inside your company, including internal forks, does not by itself trigger distribution duties.
Limits
Hold liable
The authors disclaim warranty. Recipients cannot hold them liable for damages arising from the software, except where law forbids that disclaimer.
Use trademark
The license is not a trademark license. Names, logos and product marks stay with their owners unless a separate grant says otherwise.
Patent grant
The text does not grant patents. If buyers want an express patent grant, Apache-2.0 is the usual alternative.
Obligations
Include copyright
Keep the copyright line with every copy or substantial portion you distribute.
Include license
Keep the license text with every copy or substantial portion you distribute. A web page is not a substitute for notices inside a shipped artifact.
What Multics requires when you ship
When a copy that includes Multics code leaves your company, the grant is broad and the paperwork is easy to miss. Distribution here means an installer, a mobile binary, a container image, or an SDK another team embeds. Work this list against the artifact you actually hand over, not against a README. A hosted service that never gives out a copy still belongs on the record, but the notice duty does not fire until a copy exists.
You are meeting the notice condition when the copyright and permission notices stay with any copy of the code you distribute, in source or binary form.
You are clear on the name rule when nothing in your product or your marketing presents the copyright holders as endorsing it.
You have nothing further to do in any deployment shape. There is no source duty, no network trigger, and no difference between modified and unmodified code.
The duties named in Multics
The license text itself is short. These are the named conditions. They follow the code, including files you vendor into your own repository and transitive packages in the lockfile.
Include copyright
Keep the copyright line with every copy or substantial portion you distribute.
Include license
Keep the license text with every copy or substantial portion you distribute. A web page is not a substitute for notices inside a shipped artifact.
Things to be aware of
- A historical license is waved through without storing the text, and then nobody can answer a buyer's question about it. Store the text the first time you see it.
- The identifier is guessed from a filename rather than read from the text, and the component ends up under the wrong license. Read the header before accepting it.
What the Multics License does not do
Search results often flatten Multics License into a slogan. These are the usual misreads. Multics is a grant with conditions, not a permission to skip the paperwork below.
- the Multics License does not require you to publish your own source. Combining it with closed code is the point of the grant.
- the Multics License does not mean "no obligations." The copyright line and license text still have to travel with copies you hand to other people.
- It is not a patent license unless the text says so. MIT-family grants say nothing about patents.
How Multics differs from nearby licenses
These licenses are often confused with Multics, but their release duties differ. Each row summarizes what the license requires when you ship. Open the linked page for the full checklist.
- Multics
- The Multics License is a BSD-style permissive license covering the released Multics source. Keep the notices, and do not imply an endorsement.
- BSD-3-Clause
- Permissive like MIT, with one extra rule: you may not use the authors' names to promote your product. Notices travel with source and binaries.
Common questions about Multics License
Answers to common questions about what Multics License requires, when its duties apply, and what evidence belongs with a release.
What is the Multics License?
The Multics License covers the source of Multics, the operating system whose ideas fed into Unix, released by its corporate owners and listed by the Open Source Initiative for archival reasons. It is BSD-style permissive. You may use, modify, and redistribute the code, including commercially and inside a closed product, as long as the copyright and permission notices stay with it. The one extra rule is the familiar one: you may not use the copyright holders' names to present them as endorsing your product.
What does Multics require when you ship a product?
You are meeting the notice condition when the copyright and permission notices stay with any copy of the code you distribute, in source or binary form. You are clear on the name rule when nothing in your product or your marketing presents the copyright holders as endorsing it. You have nothing further to do in any deployment shape. There is no source duty, no network trigger, and no difference between modified and unmodified code.
Does Multics require me to open my own source?
It is not a patent license unless the text says so. MIT-family grants say nothing about patents.
How do I attribute Multics in a product I ship?
Attribution for Multics means the copyright line and the license text travel with every copy a recipient actually gets. That can be an about screen, a licenses file inside the installer, or a notice in the container image. A public page helps a buyer audit the inventory. It does not replace notices inside the artifact. If you copied files into your own repository, the header on those files still has to stay.
Is a website notice enough for Multics?
No. Multics talks about copies. A public attestation page is the honest list for procurement. The condition is met when the notices sit in the material you hand over. Put them in the installer, the about screen, or a licenses file inside the binary, then keep the same texts on the page.
Do transitive Multics dependencies count?
Yes. The condition follows the code, not the package you chose by name. If the lockfile pulled in Multics transitively and you distribute that tree, those notices travel too. Listing only direct dependencies is how teams miss the duty.
How is Multics different from BSD 3-Clause License?
Multics asks this: The Multics License is a BSD-style permissive license covering the released Multics source. Keep the notices, and do not imply an endorsement. BSD 3-Clause License asks this: Permissive like MIT, with one extra rule: you may not use the authors' names to promote your product. Notices travel with source and binaries. Open the BSD 3-Clause License page for what that license requires when you ship. Do not treat the SPDX ids as interchangeable because the short names look similar.
Where do I record Multics for a buyer?
SourceTrust fetches the published artifact, extracts any license files it contains, and compares that text against the declared SPDX id. Archival code is often vendored rather than published as a package, so the fetch may find nothing and the component lands as not found. Accepting it with the text pasted in keeps the component in the inventory with an honest state instead of a blank.
Where do I record Multics for a buyer?
SourceTrust fetches the published artifact, extracts any license files it contains, and compares that text against the declared SPDX id. Archival code is often vendored rather than published as a package, so the fetch may find nothing and the component lands as not found.
Accepting it with the text pasted in keeps the component in the inventory with an honest state instead of a blank. Read /docs/inventory-compliance for the org-wide view.
See also
The hub is the pillar for this cluster. Sibling licenses are the other spokes. Product FAQ links explain how SourceTrust records the duty, not the license text itself.
Practical guidance for procurement review, not legal advice. Confirm high-stakes use with counsel.