Organization
LMSYS (Large Model Systems Organization)
Research lab · Nonprofit research · Open-source steward
LMSYS is a 501(c)(3) nonprofit that incubates open-source AI projects and research. It began in 2023 as a collaboration among UC Berkeley, Stanford, UC San Diego, Carnegie Mellon, and MBZUAI, and was incorporated as a nonprofit in September 2024. Its projects include the SGLang serving engine, FastChat, RouteLLM, and the Vicuna models.12
Status: Chatbot Arena, formerly an LMSYS project, moved to its own site in September 2024, and LMSYS now lists it as graduated. Arena Intelligence Inc., a separate company formed in 2025, operates the platform, now called Arena. LMSYS says it continues as an incubator for new projects.516
Key facts
What is and isn’t public
Products
No product records yet.
Related open artifacts
Runtimes
- SGLangSoftwareAvailability: Public
Notable documented facts
- The SGLang repository states that the project is currently hosted under LMSYS.7
- A July 2026 post on the LMSYS blog, credited to RadixArk and Google, states that RadixArk, a company, is a maintainer of the SGLang project. RadixArk's website says the company builds on SGLang for inference and will keep investing in it.910
U.S. eligibility
Eligible · basis: U.S. nonprofit or lab
LMSYS's about page names the organization Large Model Systems (LMSYS Corp.) and states that it is a 501(c)(3) nonprofit, incorporated as a nonprofit in September 2024. The IRS exempt-organization extract for California lists LMSYS Corp, with a Sacramento, California address, as a 501(c)(3) corporation with a September 2024 ruling date. No LMSYS page states a headquarters address, so the headquarters field is left empty.134
Sources
This listing is not an endorsement or a federal approval.