Arena's Valuation Hits $3.1B in 10 Months

Arena closed a $200 million Series B on Thursday at a $3.1 billion valuation, Lightspeed Venture Partners and Khosla Ventures leading the round with Salesforce Ventures, Dell Technologies Capital, a16z, Felicis, 01 Advisors, and Endeavor Catalyst also writing checks. The number matters because of how fast it moved. Back in January, Arena raised a $150 million Series A at $1.7 billion, when annualized revenue sat at $30 million.

By June, that figure had hit $100 million. Ten months, valuation nearly doubled.

The company started in 2023 as a UC Berkeley research project, letting anyone submit a prompt and vote on which AI model answered it better. That crowdsourced format now pulls in tens of millions of visitors a month, still free for regular users. Last September, Arena turned that data into a business, launching AI Evaluations, a paid service that hands model labs and enterprises detailed performance breakdowns built from community votes. The launch lined up with a growing problem in the industry: AI companies found their models were scoring well on standard benchmarks without actually improving, and enterprises needed a way to judge models against their own real-world tasks instead.