There’s a new AI model family on the block, and it’s one of the few that can be reproduced from scratch.

On Tuesday, Ai2, the nonprofit AI research organization founded by the late Microsoft co-founder Paul Allen, released OLMo 2, the second family of models in its OLMo series. (OLMo is short for “open language model.”) While there’s no shortage of “open” language models to choose from (e.g., Meta’s Llama), OLMo 2 meets the Open Source Initiative’s definition of open source AI, meaning the tools and data used to develop it are publicly available.

The Open Source Initiative, the long-running institution that aims to define and “steward” all things open source, finalized its open source AI definition in October. But the first OLMo models, released in February, met the criterion as well.

“OLMo 2 [was] developed start-to-finish with open and accessible training data, open-source training code, reproducible training recipes, transparent evaluations, intermediate checkpoints, and more,” AI2 wrote in a blog post. “By openly sharing our data, recipes, and findings, we hope to provide the open-source community with the resources needed to discover new and innovative approaches.”

There are two models in the OLMo 2 family: one with 7 billion parameters (OLMo 7B) and one with 13 billion parameters (OLMo 13B). Parameters roughly correspond to a model’s problem-solving skills, and models with more parameters generally perform better than those with fewer parameters.

Like most language models, OLMo 2 7B and 13B can perform a range of text-based tasks, like answering questions, summarizing documents, and writing code.

To train the models, Ai2 used a dataset of 5 trillion tokens. Tokens represent bits of raw data; 1 million tokens is equal to about 750,000 words. The training set included websites “filtered for high quality,” academic papers, Q&A discussion boards, and math workbooks “both synthetic and human generated.”

Ai2 claims the result is models that are competitive, performance-wise, with open models like Meta’s Llama 3.1 release.

“Not only do we observe a dramatic improvement in performance across all tasks compared to our earlier OLMo model but, notably, OLMo 2 7B outperforms Llama 3.1 8B,” Ai2 writes. “OLMo 2 [represents] the best fully-open language models to date.”

The OLMo 2 models and all of their components can be downloaded from Ai2’s website. They’re under Apache 2.0 license, meaning they can be used commercially.

There’s been some debate recently over the safety of open models, what with Llama models reportedly being used by Chinese researchers to develop defense tools. When I asked Ai2 engineer Dirk Groeneveld in February whether he was concerned about OLMo being abused, he said that he believes the benefits ultimately outweigh the harms.

“Yes, it’s possible open models may be used inappropriately or for unintended purposes,” he said. “[However, this] approach also promotes technical advancements that lead to more ethical models; is a prerequisite for verification and reproducibility, as these can only be achieved with access to the full stack; and reduces a growing concentration of power, creating more equitable access.”