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Arena, the AI leaderboard everyone uses, is now a $100M business
Arena, an AI leaderboard provider that originated as a UC Berkeley research project in 2023, has reached $100 million in annualized run-rate revenue just eight months after launching its commercial service. Best known for its crowdsourced AI model performance leaderboard generated from over 10 million user evaluations, Arena’s consumer website lets users compare two models by typing a prompt and choosing the better response. While the leaderboard remains free, the company began generating revenue in September 2024 with AI Evaluations, a service providing model labs and enterprises with deep-dive performance analytics from its community. Co-founder and CEO Anastasios Angelopoulos noted that many still view Arena as an open-source project, despite its revenue milestone. He clarified that the company charges for “consumption,” so revenue is not recurring. Arena competes with human labeling startups like Mercor, Surge, and Scale AI for post-training optimization services, as AI providers increasingly seek to maximize model performance. In January, Arena announced a $150 million Series A at a $1.7 billion post-money valuation, with annualized revenue of $30 million. For context, Handshake’s gross annualized revenue from AI training nearly doubled to $1 billion by April, while Mercor’s topped $1 billion earlier this year. Arena ranks models on text, coding, vision, image generation, and complex workflows via its new Agent Mode. Co-founded by Angelopoulos, Wei-Lin Chiang (CTO), and renowned UC Berkeley professor Ion Stoica (who advised before incorporation in April 2025), Arena has raised $250 million from investors including Felicis, Andreessen Horowitz, The House Fund, LDVP, Kleiner Perkins, Lightspeed Venture Partners, Laude Ventures, and UC Investments.