Open-weight models and licences
Downloading a model does not mean you may use it any way you like. Learn the difference between open weights and open source, and how to read a model licence.
In 60 seconds
Open-weight models and licences
Downloading a model does not mean you may use it any way you like. Learn the difference between open weights and open source, and how to read a model licence.
Open weights vs open source
| Term | What you usually get | What it does not promise |
|---|---|---|
| Open weights | The trained model files, so you can run and often fine-tune it | The training data, the full training code, or freedom to use it for anything |
| Open source (software sense) | Code under a licence that allows use, study, change and sharing, for any purpose | That the model's training data is published |
| Open source AI (stricter sense) | Weights, code and enough information about the data to rebuild or truly study the model | It is still debated exactly where the line is |
Five questions to ask every licence
- Commercial use: may I use it in a product that earns money? Are there limits, for example on company size or number of users?
- Attribution: must I name the model, keep a notice file, or show text like "built with …"?
- Acceptable-use rules: is there a list of banned uses? Do I have to pass these rules on to my users?
- Derivatives: if I fine-tune it, what licence covers my new model? Must I use a certain name?
- Outputs: may I use the model's outputs to train another model? Some licences and terms limit this.
Common licence families
- Permissive licences such as Apache 2.0 and MIT: broad freedom, including commercial use, with conditions such as keeping the licence and notices.
- Custom model licences: written by the model's publisher. They may allow commercial use but add acceptable-use policies, user limits or naming rules.
- Non-commercial or research-only licences: fine for learning and experiments, not for a paid product.
Read the model card too
- "It's on the internet, so it's free to use"
- Reading only the short licence name on the page
- Assuming a fine-tuned copy has the same licence as the original
- Opening and reading the full licence file
- Checking the acceptable-use policy and any user or revenue limits
- Checking both the base model's and the fine-tune's licences
Watch and read more
Lab
A licence checklist for two real open-weight models, and a choice for one project.
The problem
Your project: "a paid app that helps small shop owners in Tamil Nadu write replies to customer messages in Tamil and English."
- On Hugging Face, pick two small open-weight text models. Open each model card and its full licence file.
- For each, fill in a table: licence name, commercial use allowed? (and any limits), attribution needed, acceptable-use policy (yes/no, and one example rule), rules about fine-tuned versions, rules about using outputs to train other models, languages listed on the model card.
- Write the date and the exact model name and version you checked.
- Choose one model for the project and give two reasons. Write one question you would ask a lawyer.
You are done when
Hard questions
Try to answer before you reveal. If you can answer these, you understood the lesson.
Q1A model's weights are under a permissive licence, but its model card says it was trained on data with unclear rights. Is it safe to use commercially?Reveal
Not automatically. The licence covers what the publisher grants you, but it cannot remove every risk that comes from the training data. For low-risk uses many teams accept this, but for a serious product you should read the card carefully, look for any legal notes from the publisher, and get legal advice. Keep a record of what you checked.
Q2Why might a licence ask you to pass its acceptable-use policy on to your own users?Reveal
Because the publisher cannot control what your users do with your app. Passing the rules down (for example through your terms of service) means the restrictions follow the model wherever it is used. If you ignore this, you may be breaking the licence even if you personally never misuse the model.
Questions people ask
If a model is on Hugging Face, can I use it commercially?
Not automatically. Hugging Face hosts models under many different licences. Some allow commercial use, some do not, and some add conditions. Always read the licence of that exact model.
What is an acceptable-use policy?
A list of things you may not use the model for, such as illegal activity or certain harmful uses. Some licences require you to make your own users follow the same rules, for example in your app's terms.
Does a fine-tuned model keep the original licence?
Usually the base model's licence still applies to your fine-tuned version, and it may say how you must name or share it. A fine-tune someone else published may also add its own terms. Check both.
Is using a model for a college project different?
Many licences are more relaxed about research and personal learning, and non-commercial licences are made for exactly this. But if the project later becomes a product or startup, check the licence again before you launch.
Lesson test
5 questions. Get 3 right (60%) to pass and complete this lesson.