tech
January 22, 2026
Sources: Project SGLang spins out as RadixArk with $400M valuation as inference market explodes
SGLang, which originated as an open source research project at Ion Stoica’s UC Berkeley lab, has raised capital from Accel.
TL;DR
- RadixArk, the commercial company behind the open-source AI tool SGLang, has been valued at around $400 million.
- SGLang helps AI models run faster and cheaper, with companies like xAI and Cursor using it.
- The startup was founded by Ying Sheng, a former engineer at xAI and researcher at Databricks.
- RadixArk focuses on optimizing inference processing, a significant cost factor in AI services.
- This trend is seen with other projects like vLLM, which is reportedly in talks for significant funding.
- Both SGLang and vLLM originated from Ion Stoica's lab at UC Berkeley.
- RadixArk is developing SGLang as an open-source engine and Miles, a framework for reinforcement learning.
- The startup has begun charging for hosting services, while its tools largely remain free.
- Other AI inference infrastructure startups like Baseten and Fireworks AI have also recently secured substantial funding.