Chatbot Arena, a platform designed to compare the performance of various AI models, has raised $100m in seed funding.

The round was led by Andreessen Horowitz (a16z) and UC Investments (University of California), with participation from Lightspeed, Laude Ventures, Felicis, Kleiner Perkins, and The House Fund.

The round values the company at $600m, according to a Bloomberg report.

The funding coincides with the upcoming relaunch of LMArena, featuring a fully rebuilt platform designed to enhance AI evaluation with greater rigor, transparency, and user focus.

The platform, which originated as an academic project at UC Berkeley, enables researchers, developers, and users to assess how AI models perform in real-world scenarios.

More than 400 model evaluations have been conducted on LMArena, with more than three million votes cast, influencing both proprietary and open-source models from companies such as Google, OpenAI, Meta, and xAI, the company said.

LMArena co-founder and CEO Anastasios Angelopoulos said: “In a world racing to build ever-bigger models, the hard question is no longer what can AI do. Rather, it’s how well can it do it for specific use cases, and for whom. We’re building the infrastructure to answer these critical questions.”

The relaunched LMArena, set to debut in late May 2025, incorporates community feedback and introduces a rebuilt user interface, mobile-first design, lower latency, and new features like saved chat history and endless chat.

Ion Stoica, co-founder and UC Berkeley professor, said: “AI evaluation has often lagged behind model development. LMArena closes that gap by putting rigorous, community-driven science at the centre. It’s refreshing to be part of a team that leads with long-term integrity in a space moving this fast.”

The company collaborates with model providers to identify performance trends, gather human preference data, and test updates in real-world conditions, aiming to develop advanced analytics and enterprise services while keeping core participation free.

“We invested in LMArena because the future of AI depends on reliability,” said Anjney Midha, general partner at a16z. “And reliability requires transparent, scientific, community-led evaluation. LMArena is building that backbone.”

Jagdeep Singh Bachher, chief investment officer at UC Investments, said: “We’re excited to see open AI research translated into real-world impact through platforms like LMArena. Supporting innovation from university labs such as those at UC Berkeley is essential for building technologies that responsibly serve the public and advance the field.”