Arena hits $100 million in annualized run-rate revenue

Arena, an AI leaderboard provider that originated as a research project at UC Berkeley in 2023, has reached $100 million in annualized run-rate revenue (ARR). The milestone comes just eight months after the company launched its commercial service. Arena is widely known for its crowdsourced AI model performance leaderboard, which is generated from over 10 million user evaluations. On its website, users prompt two models and select which response is better. While the public leaderboard remains free, the company began generating revenue in September when it introduced AI Evaluations, a commercial service providing performance analytics gathered from its community.

Although Arena refers to this milestone as ARR, co-founder and CEO Anastasios Angelopoulos clarified that the revenue is consumption-based rather than recurring. “A lot of people don’t even understand that our business is making any money at all; people still see us as an open source project,” Angelopoulos said. He noted that the company competes for the same dollar with human labeling startups such as Mercor, Surge, and Scale AI, which assist model makers in refining AI during post-training. While Arena lacks direct crowdsourced competitors—following the shutdown of rival startup Yupp in March—its commercial offerings also include Agent Mode, a feature for complex, long-running workflows.

The startup incorporated as a company in April 2025, co-founded by Angelopoulos, CTO Wei-Lin Chiang, and UC Berkeley professor Ion Stoica, who advised the project before its incorporation. Arena has rapidly scaled its financial footprint:

• Total funding raised: $250 million from investors including Felicis, Andreessen Horowitz, The House Fund, LDVP, Kleiner Perkins, Lightspeed Venture Partners, Laude Ventures, and UC Investments.
• Series A round: $150 million announced in January at a post-money valuation of $1.7 billion.
• Revenue growth: Annualized revenue stood at $30 million in January.

This growth occurs alongside surging revenues for other AI training and labeling companies. In April, The Information reported that industry peer Handshake saw its gross annualized revenue nearly double from $550 million in January to nearly $1 billion. Meanwhile, Mercor’s annualized revenue reached $1 billion earlier this year, up from $500 million last September, according to The Information.

Why it matters

Arena’s rapid revenue growth shows that its commercial offerings are as popular with customers as they are with its community of evaluators, who are frequently drawn to the platform for early access to the latest, often unreleased, AI models.