Ai2

Ai2 (the Allen Institute for AI) is a nonprofit AI research lab based in Seattle. It was founded in 2014 by Microsoft co-founder Paul Allen.

What sets it apart is the scope of what it releases. Most models called "open-source" today only release the weights of the finished model, keeping what and how it was trained on hidden. Ai2 releases the training data, code, and even intermediate stages in full. To put it in cooking terms: instead of just handing you the finished dish, it gives you the ingredient list and the cooking process too.

Because of this, the lab's models are discussed more for their research value than for leaderboard rankings. You can dig into the "why was it trained this way" question here in a way you can't elsewhere.

In August 2026, Ai2 expanded its partnership with Hugging Face and tripled its public storage capacity. For a lab that publishes its entire training process, storage capacity directly determines how much it can disclose, so even though the number sounds small, it's a substantive expansion for this lab.

When you see the phrase "fully open model," it's usually referring to this lab. It's used to distinguish from models that only release their weights.