Lukas Biewald

Biewald's 2019 essay on starting a second machine learning tools company recounts working on search before concluding, by 2007, that access to training data was the main obstacle for machine learning teams. Biewald left that job to start CrowdFlower, later renamed Figure Eight, which created labeled training data sets for companies.3

After stepping down as CEO of Figure Eight, Biewald spent time building deep learning projects and teaching introductory deep learning classes to engineers. Biewald then started Weights & Biases with longtime co-founder Chris Van Pelt and new co-founder Shawn Lewis; the company's about page dates the founding to 2017 and notes that CoreWeave acquired it in May 2025.31

Weights & Biases began with an experiment tracking tool developed to help build models at OpenAI, and Biewald's essay frames the product as basic software and best practices for managing machine learning models, which cannot be read or diffed like ordinary code. The company's Python SDK is published as open source under the MIT license.135

Biewald's publications page lists research co-authored with Daphne Koller on word-sense disambiguation for machine translation (EMNLP 2005) and papers on crowdsourcing quality, alongside guest articles on hardware and machine learning projects, such as a guide to building a deep learning machine.4