Arena, the company behind the popular LMArena AI leaderboard, has raised a $200 million Series B round at a $3.1 billion valuation, it said on Thursday.
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 joining. Arena previously announced a $150 million Series A in January at a $1.7 billion post-money valuation, when its annualized revenue was $30 million. Its valuation has nearly doubled in about 10 months.
Arena said it reached $100 million in annualized run-rate revenue in June. The company provides a crowdsourced platform that is free for consumers, where people enter prompts or request vibe-coded projects and rate which model does it better. Arena claims it has tens of millions of monthly visitors.
In September of last year, Arena introduced its commercial product, AI Evaluations, which provides model labs and enterprises with detailed performance analytics based on community feedback. The company said AI labs have realised their models were gaming benchmarking tests, while enterprises wanted help determining which model works best for their own internal needs.
Arena has also added an alignment category to its leaderboard, ranking models on issues including unauthorized action, false attribution and what it calls deceptive completion. Currently, a slate of OpenAI's models are at the top of its preliminary alignment leaderboard, with Claude Opus 5.5 and Claude Fable in sixth and ninth place, respectively.