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Weights and Biases
Acquired by CoreWeave · 2025 · $1.7B
Weights and Biases was an Observability and AI Monitoring company founded in 2017 and based in San Francisco, United States. It was acquired by CoreWeave in 2025 for $1.7B.
ML experiment tracking and model monitoring platform used by OpenAI, NVIDIA, and Meta to track training runs, evaluate models, and monitor production machine learning systems. Acquired by CoreWeave for $1.7B in May 2025; previously used by 1,000+ organizations including major foundation model labs; added LLM evaluation and monitoring capabilities; strong in AI research.
W&B's platform tracks the AI models that power coding tools, making it the meta-observability layer for the foundation models that enable AI-assisted development.
At a glance
Total raised
$235M
Headcount
201-500
Headquarters
San Francisco
United StatesFounded
2017
Status
Acquired
Subsector
Funding history
Total raised
$235M
Rounds tracked
4
Latest stage
Acquired
| Date | Stage | Amount | Valuation | Lead investors |
|---|---|---|---|---|
| Aug 9, 2023 | Growth | $50M | $1.3B | Nat Friedman, Daniel Gross |
| Oct 13, 2021 | Series C | $135M | $1B | Felicis Ventures, BOND |