RadixArk Commands $400M Valuation as SGLang Team Pivots to Commercial AI Infrastructure

The open-source tools powering xAI and Cursor are officially going commercial. RadixArk, a startup born from the SGLang project, has reportedly secured a $400 million valuation, marking a major shift in the AI inference landscape.

RadixArk vLLM inference funding 2026: Scaling the Backbone

According to TechCrunch, Accel led the investment in RadixArk. The company was co-founded by CEO Ying Sheng, a former xAI engineer and Databricks research scientist. The startup originated in Ion Stoica's lab at UC Berkeley—the same prestigious incubator that produced Databricks.

While SGLang remains open-source, RadixArk is diversifying its revenue by offering hosting services and building 'Miles,' a specialized framework for reinforcement learning. The startup previously attracted angel capital from industry heavyweights, including Intel CEO Lip-Bu Tan.

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A Billion-Dollar Race for Inference Efficiency

RadixArk isn't alone in this transition. vLLM, another UC Berkeley offspring, is reportedly in talks to raise over $160 million at a $1 billion valuation, with a16z expected to lead. Despite vLLM co-founder Simon Mo calling certain details inaccurate, the momentum in the inference infrastructure layer is undeniable.

The surge in funding for RadixArk and vLLM follows a broader market trend. Recently, Baseten secured $300 million at a $5 billion valuation, while Fireworks AI hit a $4 billion valuation last October.