ITG NowHome › AI glossary › Closed model
What is a closed AI model?
Short answer
A closed model is an AI model whose files are kept private, so you can only use it through the maker's app or service.
- Category Models
- Also called closed-weight model, proprietary model, closed AI model
- Updated 20 Oct 2026
Closed model, explained simply
The company runs the model on its own computers. You send a request and get a reply back.
This often means easy setup and strong results, but you can't download it, change it or run it offline.
ChatGPT and Claude are examples of services built on closed models.
On ITG Now, our AI models page shows open and closed models together so you can compare them.
Related terms
Open weightsModel weightsFrontier modelAPILocal AI
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Questions people ask about Closed model
Closed model vs open model: which is better?
Neither always wins. Closed models are easy to start with. Open ones give you more control and privacy.
Is a closed model less safe?
Not by default. Safety depends on how the maker builds and runs it, and how you use it.