Weights & Biases (W&B) is the AI developer platform that the world's leading machine learning teams use to build, train, and deploy better models faster. Founded in 2017 in San Francisco, W&B provides experiment tracking, model management, and LLMOps tooling used by over 1 million developers - from OpenAI and Meta to Toyota and AstraZeneca. Acquired by CoreWeave in May 2025 for $1.7 billion, W&B is now the software backbone of one of the most important AI infrastructure companies in the world.
Weights & Biases (W&B) is the leading AI developer platform for machine learning and generative AI, offering tools for experiment tracking, hyperparameter optimization, model registry, and LLM application development. Founded in 2017 by Lukas Biewald, Chris Van Pelt, and Shawn Lewis in San Francisco, W&B powers over 1 million developers and 1,400+ organizations — including OpenAI, Meta, and NVIDIA — by making it easier to build, train, evaluate, and deploy AI models. Acquired by CoreWeave for ~$1.7B in May 2025, W&B continues expanding its platform with Weave for LLM/agent observability, cementing its position as the de facto infrastructure for modern AI development.