One of the more prolific AI and machine learning development platforms, Weights & Biases has secured a new tranche of cash from ex-GitHub CEO Nat Friedman and former Y Combinator partner Daniel Gross. Friedman and Gross, alongside existing investors Coatue, Insight Partners, Felicis, Bond, BloombergBeta and Sapphire, have invested $50 million in Weights & Biases in a strategic round that values the company at $1.25 billion. Bringing the startup's total raised to $250 million, the investment comes as Weights & Biases prepares to launch Prompts, a new product designed to help users monitor and evaluate the performance of large language models (LLMs) along the lines of OpenAI's GPT-4.