open-source AI
In plain wordsAI released, ideally with its code and details of its training data and not just the finished model, so that anyone may use, inspect, alter, share and even rebuild it. How open is open enough is debated.
An AI model or system whose release carries over to AI the freedoms that open-source licenses secure for software, and supplies the materials needed to exercise them. The most cited benchmark, the Open Source Initiative's Open Source AI Definition 1.0 (October 2024), lists the freedoms as using the system for any purpose, studying how it works, modifying it and sharing it, and requires the preferred form for making changes: the model parametersweights, n.: The learned numbers inside a neural network that set how strongly each part influences the next. The finished set of weights is, in effect, the trained model itself., the full code for training and running it, and enough information about the training data for a skilled person to build a 'substantially equivalent system', though not necessarily the data itself, a compromise criticized from both sides. Few prominent models qualify; examples cited as meeting the bar include EleutherAIEleutherAI, prop. n.: An open-science research group, begun by online volunteers in 2020, that released some of the first large language models anyone could download, along with the text collections used to train them.'s Pythia and the Allen Institute for AIAllen Institute for AI, prop. n.: Paul Allen, a co-founder of Microsoft, created this nonprofit Seattle AI lab in 2014. It is known for releasing models together with everything used to build them, and for the Semantic Scholar paper search engine.'s OLMo, which publish data, code and checkpoints. The label is widely applied to open-weight modelsopen-weight model, n.: An AI model whose trained internal numbers are published for anyone to download and run on their own computers, even if the data and code used to make it stay private. with restrictive licenses, a practice critics call open-washing, and openness is increasingly assessed as a gradient across components rather than a yes-or-no property.
Under the OSI definition, a model whose license bans use by competitors cannot be called open-source AI.
Origin
Open-source principles date from the free-software movement of the 1980s and the Open Source Definition of 1998. Applying them to machine learning became contentious in 2023, when Meta described its restrictively licensed Llama 2 as open source; the Open Source Initiative ran a two-year consultation and published the Open Source AI Definition 1.0 in October 2024.
Usage note
Debate centers on training data: some argue that without it a model cannot be studied or rebuilt and so is not truly open; others reply that legal and privacy limits on sharing data would make such a standard unattainable. The EU AI ActEU AI Act, prop. n.: The European Union's law on artificial intelligence, the first broad AI law anywhere: it bans some uses, sets strict checks for risky ones and puts duties on the makers of the biggest AI models. grants limited exemptions to models released under free and open-source licenses.
Related
- open-weight modelopen-weight model, n.: An AI model whose trained internal numbers are published for anyone to download and run on their own computers, even if the data and code used to make it stay private.
- model licensemodel license, n.: The legal terms under which an AI model may be downloaded and used — for example, whether businesses may use it, whether changes may be shared, and which uses are banned.
- proprietary modelproprietary model, n.: An AI model kept private by the company that made it; outsiders can use it only through the company's apps or paid online services and can never download it.
- Hugging FaceHugging Face, prop. n.: A company whose website is the main public library for sharing AI models and datasets — often called the GitHub of machine learning — and which makes widely used free AI software.
- data licensingdata licensing, n.: The legal permissions that say who may use a dataset or a body of content, for what purposes and on what terms — including whether it may be used to train AI.
- EU AI ActEU AI Act, prop. n.: The European Union's law on artificial intelligence, the first broad AI law anywhere: it bans some uses, sets strict checks for risky ones and puts duties on the makers of the biggest AI models.
- proprietary modelproprietary model, n.: An AI model kept private by the company that made it; outsiders can use it only through the company's apps or paid online services and can never download it.
Sources
- Open Source Initiative (2024). The Open Source AI Definition 1.0.
- Liesenfeld, A. & Dingemanse, M. (2024). Rethinking open source generative AI: open-washing and the EU AI Act. Proceedings of ACM FAccT 2024.
Mentioned in
LlamaLlama, prop. n.: A family of AI language models from Meta, first released in 2023, whose trained settings can be downloaded and run by anyone, making them the foundation for thousands of other AI projects., open-weight modelopen-weight model, n.: An AI model whose trained internal numbers are published for anyone to download and run on their own computers, even if the data and code used to make it stay private., proprietary modelproprietary model, n.: An AI model kept private by the company that made it; outsiders can use it only through the company's apps or paid online services and can never download it., Stable DiffusionStable Diffusion, prop. n.: A widely used image-generating AI whose model files were released for anyone to download, so people could run it on their own computers and adapt it., Allen Institute for AIAllen Institute for AI, prop. n.: Paul Allen, a co-founder of Microsoft, created this nonprofit Seattle AI lab in 2014. It is known for releasing models together with everything used to build them, and for the Semantic Scholar paper search engine., effective accelerationismeffective accelerationism, n.: An online movement, known as e/acc, that wants AI and other technology developed as fast as possible, arguing that progress is good and that safety-driven regulation does more harm than good., EleutherAIEleutherAI, prop. n.: An open-science research group, begun by online volunteers in 2020, that released some of the first large language models anyone could download, along with the text collections used to train them., GemmaGemma, prop. n.: Google's family of free-to-download AI language models: smaller relatives of its Gemini systems, compact enough to run on a single computer and, in some versions, on a phone., gpt-ossgpt-oss, prop. n.: Two free-to-download reasoning models released by OpenAI in August 2025 — its first downloadable language models since 2019 — that anyone may run, modify and use commercially on their own hardware., model licensemodel license, n.: The legal terms under which an AI model may be downloaded and used — for example, whether businesses may use it, whether changes may be shared, and which uses are banned., Agentic AI FoundationAgentic AI Foundation, prop. n.: A nonprofit group under the Linux Foundation that looks after shared, open technical standards for AI agents, such as the Model Context Protocol, so that no single company controls them., marginal riskmarginal risk, n.: How much extra danger an AI model adds compared with what people could already do without it — for instance with search engines, textbooks or models that are already freely available., Open Source InitiativeOpen Source Initiative, prop. n.: A nonprofit group that decides what counts as 'open source' software and, in 2024, published a definition of what makes an AI system genuinely open source., Product Liability DirectiveProduct Liability Directive, prop. n.: The EU law that lets people claim compensation, without proving anyone was careless, when a defective product injures them — rewritten in 2024 so that software and AI count as products., PyTorch FoundationPyTorch Foundation, prop. n.: A nonprofit group, part of the Linux Foundation, that owns and steers the free PyTorch software for building AI so that no single company controls it. It now also looks after related projects.