SAM 3 License: What You Can Do, What You Can’t, and What It Means in Practice

Quick note: this is an informal explanation to help you understand the SAM 3 license. It’s not legal advice. For anything serious (startup, client work, etc.), a lawyer should review the actual license text.

---

1. What is the SAM 3 License?

Segment Anything Model 3 (SAM 3) is released by Meta under a custom license called the SAM License (updated November 19, 2025). It covers the models, weights, code, and documentation (“SAM Materials”) for SAM 3 and closely related projects (like SAM 3D).

This license is:

• Open: you can download the code and weights, run them locally, modify them, and build on top of them.

• Permissive but not “standard open source”: it’s not MIT/Apache/GPL. It’s a custom license with extra conditions, especially around:

  • Military / warfare / ITAR-related uses

  • Export controls and sanctions

  • Reverse engineering

  • Litigation / patent claims

Meta themselves explicitly say SAM 3 is shared under the SAM License so others can build their own experiences. Independent write-ups also describe SAM 3 as “open source under a custom SAM License” that allows both research and commercial use with restrictions.

---

2. What Counts as “SAM Materials”?

The license defines “SAM Materials” very broadly:

• Model code

• Trained weights

• Inference / training / fine-tuning code

• Documentation and specs

• Other elements that ship as part of SAM 3

Basically, if you download SAM 3 from the official GitHub (facebookresearch/sam3), Hugging Face, or official Meta links, you’re almost certainly dealing with SAM-Licensed materials.

---

3. Big Picture: What Does the SAM 3 License Allow?

At a high level, the SAM License gives you a wide set of rights:

• Use the SAM Materials

• Reproduce and copy them

• Modify and create derivative works

• Distribute SAM 3 and your derivatives

• Commercial use is allowed, as long as you follow the rules

It even includes a patent license from Meta for patents that are necessarily used by SAM 3, which is similar in spirit to what you see in licenses like Apache 2.0 (though this is not Apache).

So: yes, you can build products, internal tools, and services that use SAM 3 but certain uses are explicitly forbidden (see below).

---

4. Redistribution: If You Share SAM 3 or Your Fork

If you share SAM 3 or something built directly on SAM 3, the license imposes some obligations:

1. You must keep it under the same SAM License.

   • If you distribute the SAM Materials or derivatives, you must distribute them under this same agreement.

   • You also have to include a copy of the SAM License with what you share.

2. You must acknowledge SAM 3 in research publications.

   • If you publish research using SAM 3, you must say that you used SAM Materials.

3. You must obey applicable laws, including:

   • Export controls & sanctions

   • Local privacy / data protection laws

   • Other relevant regulations

So you can’t just relicense SAM 3 under MIT or your own custom license. You also can’t quietly remove Meta’s license and pretend SAM 3 is fully your own open-source project.

---

5. Key Restrictions: What You Cannot Do

This is the part most people care about. The SAM License places several clear restrictions.

5.1 No Military / Warfare / ITAR Uses

The license explicitly bans using SAM 3 for:

• ITAR-related activities (U.S. export controls for military/defense tech)

• Military or warfare purposes

• Nuclear industry or applications

• Espionage

• Development or use of guns or illegal weapons

So if someone wants to use SAM 3 in a weapons system, military surveillance pipeline, or other defense-tech context, the license says no.

This is also why some articles mention SAM 3’s license as “open but not defense-friendly” or call out the “explicit prohibition of military end-use.”

5.2 Trade Controls and Sanctions

The license repeatedly references “Trade Controls” and “Sanctions”:

• You can’t be a sanctioned person/entity.

• You can’t use SAM 3 in violation of U.S., EU, UK, UN sanctions or export/import controls.

So if a particular country or user is under sanctions, they’re not allowed to legally use SAM 3 under this license.

5.3 No Reverse Engineering of SAM 3 Itself

The license also says your use must not involve reverse engineering, decompiling, or discovering underlying components of the SAM Materials.

In other words:

• You can:

  • Inspect the open-source code (it’s on GitHub).

  • Fine-tune or extend SAM 3 using the provided APIs.

• You can’t:

  • Try to break down the compiled parts to uncover hidden pieces Meta didn’t expose.

  • Treat the weights as something to be “cracked open” beyond what the repo already gives you.

5.4 Outputs and “Misuse”

The license doesn’t micro-regulate every possible output you can produce, but it does:

• Emphasize that you’re responsible for how you use SAM 3 and its outputs.

• Require that your use complies with laws, privacy rules, and trade controls.

If you build a product using SAM 3 that violates these rules, you are the one in trouble, not Meta.

---

6. Patent Rights and When They End

The SAM License includes a patent grant that allows you to use SAM 3 without worrying about certain Meta patents—as long as you don’t sue people over those patents.

Two key termination clauses:

1. If you sue someone alleging SAM 3 infringes your patents
   → The patent license you were granted terminates.

2. If you sue Meta or others saying SAM 3 or its outputs infringe your rights
   → All licenses you have under this agreement can be terminated.

This is similar to how some open-source licenses discourage patent aggression: “If you start a patent fight, you lose your rights under this license.”

---

7. Who Owns What? (IP & Derivatives)

The license draws a clear line between:

• Meta’s ownership of the original SAM Materials and any derivatives created by or for Meta.

• Your ownership of derivative works that you create from SAM 3.

So:

• If you fine-tune SAM 3 on your dataset, you generally own your modifications, subject to the SAM License (you still have to obey it).

• You do not gain ownership over the original SAM 3 weights or code.

• You can’t remove Meta’s rights or license terms from SAM 3 itself.

However, because your derivatives are still “SAM Materials” for licensing purposes, if you distribute them, the SAM License flows through with them.

---

8. Warranties, Liability, and “Use at Your Own Risk”

As usual with big AI models, the SAM License contains strong disclaimers:

• SAM 3 and its outputs are provided “as is”.

• No warranties of:

  • Fitness for a specific purpose

  • Non-infringement

  • Merchantability

• You are responsible for:

  • Deciding whether SAM 3 is appropriate for your use case

  • Handling any risks from using SAM 3 or its outputs

Meta also limits their liability for damages. So if you build a tool on SAM 3 and something goes wrong (e.g., a segmentation mistake causes some business damage), you can’t realistically claim Meta owes you compensation.

---

9. Termination: When Do Your Rights End?

Your rights under the SAM License continue as long as you follow the terms. Meta can terminate the agreement if:

• You breach the license (e.g., using SAM 3 for prohibited purposes, violating trade controls, reverse engineering, etc.).

• You file certain kinds of lawsuits against Meta (as discussed above).

If terminated, you must:

• Stop using SAM 3

• Delete the SAM Materials in your possession (according to the license)

Some sections (like disclaimers and limitations of liability) remain in effect even after termination.

---

10. Is SAM 3 “Open Source”?

This is a bit subtle:

• Many blogs and tools refer to SAM 3 as “open source” because:

  • The code and weights are public and downloadable.

  • You can modify, redistribute, and use it commercially within limits.

• However, the license is custom and includes use-case restrictions (like banning military/ITAR use).

The Open Source Initiative (OSI) usually considers “field-of-use restrictions” incompatible with strict open-source definitions. So:

• Practically: SAM 3 behaves like a very open, permissive model.

• Formally: it’s under a custom Meta SAM License, not OSI-standard.

For your SEO/article, you can safely say something like:

“SAM 3 is released under Meta’s custom SAM License, which allows broad research and commercial use but prohibits military and ITAR-related applications.”

---

11. Typical Scenarios: What the License Means for You

Let’s break down what the SAM 3 license means in real life.

11.1 Student or Hobbyist

You want to:

• Run SAM 3 on your laptop or cloud GPU

• Experiment with image/ video segmentation

• Publish a blog or GitHub repo showing your experiments

License impact:

• ✅ Fine to download and experiment

• ✅ Fine to publish code and results (with attribution + same SAM License for SAM-based stuff)

• ✅ Fine to write tutorials and demos

• ❌ Not fine if your project is obviously for military/warfare use, or violates sanctions

11.2 Researcher / Lab

You want to:

• Use SAM 3 in academic research

• Publish papers and benchmarks

• Release fine-tuned versions of the model

License impact:

• ✅ You can use SAM 3 in research

• ✅ You can publish your results — just acknowledge SAM Materials

• ✅ You can share fine-tuned models, but they must stay under the SAM License

• ❌ You can’t relicense SAM 3 or your SAM-based models under MIT/Apache only

11.3 Startup or Company Building a Product

You want to:

• Build a SaaS product or internal tool using SAM 3

• Offer segmentation/tracking as part of your platform

• Possibly host an API that uses SAM 3 under the hood (like many companies already do)

License impact:

• ✅ Commercial use is allowed, if you:

  • Respect export/sanctions rules

  • Avoid prohibited military/ITAR/nuclear/weapon uses

  • Don’t reverse engineer or misuse the SAM Materials

• ⚠️ You must keep SAM 3 itself under the SAM License if you redistribute it (e.g., if you ship model weights to customers).

• ⚠️ For serious commercial deployment, you should have a lawyer review the SAM License, especially if you operate in sensitive regions or sectors.

11.4 Open-Source Tool Maintainer

You want to:

• Build a plugin for ComfyUI, a labeling tool, or other OSS that wraps SAM 3. (Many already exist.)

License impact:

• ✅ You can integrate SAM 3 as an optional backend.

• ✅ You can publish code that downloads SAM 3 from official sources.

• ⚠️ If you redistribute the SAM weights or SAM-based models, they must remain under the SAM License.

---

12. Practical Steps: How You “Accept” the SAM 3 License

You don’t sign a paper; acceptance happens when you use or distribute the SAM Materials. The license explicitly says that by using or distributing any SAM Materials, you agree to be bound by the terms.

In practice, you “accept” the license when you:

• Click “Accept” on a model card (e.g., on Hugging Face)

• Clone the facebookresearch/sam3 repo and use it

• Download the checkpoints from official links

If you’re just browsing the paper or Meta blog, you’re not really in license territory yet. But as soon as you use the models/weights/code, the license kicks in.

---

13. Quick FAQ Style Summary

Q1: Can I use SAM 3 for commercial projects?

Yes, commercial use is allowed, as long as you obey the SAM License (no military/ITAR use, obey sanctions, don’t reverse engineer, etc.).

Q2: Can I fine-tune SAM 3 and host my own API?

Yes. Many companies already do this. Just make sure you respect the license, and if you distribute the weights, you keep them under the SAM License.

Q3: Can I use SAM 3 for a defense or weapons project?

No. The license explicitly bans military, warfare, nuclear, espionage, and illegal weapons uses.

Q4: Is SAM 3 “Apache 2.0” or “MIT”?

No. It’s under Meta’s own SAM License, which is more restrictive in some areas (e.g., military use, reverse engineering, trade controls).

Q5: Who owns my fine-tuned version of SAM 3?

You own your modifications, but they’re still governed by the SAM License and must be distributed under it if you share them.

Q6: Do I need to cite SAM 3 in a paper?

Yes. If you publish research using SAM Materials, you must acknowledge them in your publication.

---

14. Final Thoughts: How to Think About the SAM 3 License

You can think of the SAM 3 license like this:

• Very open for most everyday and commercial uses:

  • Startups, researchers, creators, tool builders  all can use SAM 3, as long as you follow the rules.

• Strict for sensitive / defense / sanctioned uses:

  • Explicit bans around military, ITAR, nuclear, espionage, and illegal weapons.

• Custom and slightly opinionated:

  • Encourages open research and practical deployment, but draws a line around where Meta doesn’t want the tech to go.

If you’re building a normal AI product (editing tool, analytics, robotics, AR/VR, data labeling, etc.), SAM 3 is usually safe to adopt—but always double-check the license for your specific use case.