# Open weights, open code and gated models

Source: https://onco.cc/terms/open-weights/  
OnCo record `open-weights` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Open weights means a model's trained parameters are published so anyone can run and adapt it; that is less than open source, which also needs the training code and data, and more than gated weights, which require a request and a licence click.

## Summary

Open-source AI, as the Open Source Initiative defines it, is an AI system freely available to use, study, modify and share, including its training data, code and parameters (Wikipedia). Most biology foundation models fall short of this: BulkFormer released weights and code under permissive terms; UNI2 and Virchow2 are gated on Hugging Face for non-commercial research; BulkRNABert is research-only; PLUTO and Med-Gemini released nothing. OnCo's open-source map records each project's openness level rather than treating open as one thing.

## Fields

- Kind: Term
- Last checked: 2026-09-24
- Also known as: open weights; open-weight model; open-weights model; gated weights; gated model; closed weights; weights released; open-source AI
- Tags: cansim-terms

## Notes

- Listed in the CanSim terms map 1.0.0 (docs/onco/terms.json, generated 2026-09-24), CC BY 4.0, attribution: CanSim project, an open, public-data-first cancer foundation-model programme; CanSim page path /terms/open-weights.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Open-source_artificial_intelligence
- Wikipedia: https://en.wikipedia.org/wiki/Open-source_artificial_intelligence

## Connected records

- terms: [Cancer AI vocabulary (CanSim terms map)](https://onco.cc/terms/cancer-ai-vocabulary/), [Hugging Face Hub](https://onco.cc/terms/hugging-face-hub/), [Local-only language models over patient data (privacy by architecture)](https://onco.cc/terms/local-llm-reasoning-layer/), [Model cards and datasheets for datasets](https://onco.cc/terms/model-card/), [Open licences: Apache-2.0, MIT and CC BY 4.0](https://onco.cc/terms/open-licences/), [Pathology foundation models: UNI, UNI2, Virchow2, CTransPath, CONCH, TITAN](https://onco.cc/terms/pathology-foundation-models/)

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JSON: https://onco.cc/api/v1/entities/open-weights.json