AI evaluation platform Arena has raised $200 million in Series B funding at a $3.1 billion valuation, TechCrunch reports. The round was led by Lightspeed Venture Partners and Khosla Ventures, with Salesforce Ventures, 01 Advisors, Dell Technologies Capital, Endeavor Catalyst, a16z, Felicis, and others participating. The company said it reached $100 million in annualized run-rate revenue in June.
Arena began as a UC Berkeley research project in 2023 and lets consumers rate AI model outputs for free. It launched a commercial product, AI Evaluations, in September last year. The company argues that static benchmarks break down as models learn to game them, and that a neutral third party is needed to measure safety and alignment.
TechCrunch notes Arena's valuation has nearly doubled in about 10 months: its January Series A was at $1.7 billion, when annualized revenue was $30 million. The company also added an alignment category to its leaderboard, ranking models on unauthorized action, false attribution, and 'deceptive completion.' OpenAI models currently top the preliminary ranking, with Claude Opus 5.5 and Claude Fable in sixth and ninth place.