ChatGPT maker OpenAI has entered into a definitive agreement to acquire Neptune.ai, a start-up that offers tools for experiment tracking and metadata management, for an undisclosed amount.
In a statement, OpenAI says Neptune gives researchers a way to track experiments, monitor training, and understand complex model behaviour as it happens.
From its beginning, it notes that the Neptune team focused on supporting the hands-on, iterative work of model development.
More recently, Neptune has worked closely with OpenAI to develop tools that enable researchers to compare thousands of runs, analyse metrics across layers, and surface issues, it adds.
“Neptune’s depth in this area will help us move faster, learn more from each experiment, and make better decisions throughout the training process,” reads the statement.
OpenAI was founded in December 2015 as a non-profit AI research lab backed by figures such as Sam Altman, Greg Brockman and Elon Musk.
In 2019, it shifted to a “capped-profit” model to support large-scale research, a move that coincided with Microsoft’s $1 billion investment and the beginning of a deep strategic partnership. Additional funding from venture firms such as Sequoia Capital and Andreessen Horowitz pushed the company’s valuation to nearly $30 billion in 2023.
The surge in generative AI adoption, especially after ChatGPT, led to even larger rounds, as OpenAI raised $6.6 billion in 2024 at a $157 billion valuation, followed by a landmark $40 billion round in 2025 led by SoftBank, valuing the company at about $300 billion.
In September, Nvidia announced a $100 billion investment in OpenAI, as part of a strategic partnership to build one of the largest AI infrastructure deployments in history.
“Neptune has built a fast, precise system that allows researchers to analyse complex training workflows,” says Jakub Pachocki, OpenAI’s chief scientist. “We plan to iterate with them to integrate their tools deep into our training stack to expand our visibility into how models learn.”
Piotr Niedźwiedź, founder and CEO of Neptune, says: “This is an exciting step for us. We’ve always believed that good tools help researchers do their best work. Joining OpenAI gives us the chance to bring that belief to a new scale.”
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