RadixArk Secures $400M, Spinning Out SGLang as AI Inference Powerhouse

A trend is happening in the AI world: popular open-source tools are becoming venture-backed startups worth millions. the latest example is RadixArk, the company behind SGLang. SGLang helps AI models run faster and cost less.

RadixArk was recently valued at around $400 million in a funding round led by Accel, according to two sources. This is a significant amount for a startup that launched last August. TechCrunch couldn’t confirm the exact funding amount.

this news comes as the team maintaining SGLang—used by companies like xAI and Cursor to speed up AI model training—has moved to RadixArk. RadixArk started as SGLang in 2023 within the UC Berkeley lab of Databricks co-founder Ion Stoica.

The startup previously received funding from investors, including Intel CEO lip-Bu Tan, sources said.

Ying Sheng, a key person behind SGLang and a former engineer at xAI, left Elon Musk’s AI company to become the co-founder and CEO of RadixArk, according to a LinkedIn post she made last month. Sheng used to be a research scientist at Databricks.

Ying Sheng, Accel, and Lip-Bu Tan didn’t respond to requests for comment.

Both SGLang and RadixArk work on improving inference processing—essentially,