Arena (AI platform)

Last updated
Arena
Arena AI UI.png
Screenshot as of January 28, 2026
Type of site
 Artificial intelligence
Country of originUnited States
Founders
  • Wei-Lin Chiang
  • Anastasios N. Angelopoulos
  • Ion Stoica
URL arena.ai
RegistrationOptional
LaunchedMay 3, 2023;2 years ago (2023-05-03)

Arena [1] (formerly Chatbot Arena) is a public, web-based platform that evaluates large language models (LLMs) through anonymous, crowd-sourced pairwise comparisons. Users enter prompts for two anonymous models to respond to and vote on the model that gave the better response, after which the models' identities are revealed. Users can also choose models to test themselves. [2] [3]

Contents

Arena is popular within the artificial intelligence industry, with major companies supplying their large language models, such as OpenAI's GPT-4o and o1, Google DeepMind's Gemini, [4] and Anthropic's Claude, [5] and using their subsequent rankings to promote them.

The website has been used for preview releases of upcoming models. Notably, Chinese company DeepSeek tested its prototype models in the Arena months before its R1 model gained attention in Western media. [6] Other notable pre-release models include OpenAI's GPT-5 under the codename "summit" and Google DeepMind's Gemini 2.5 Flash Image (an image-generation and editing model) under the codename "Nano Banana". [7] [8]

Arena's evaluation methodology for large language models has been examined in academic analyses, which have identified specific limitations and suggested areas for improvement. The platform is an active contributor of the AI research ecosystem and has since implemented methodological updates in coordination with ongoing research through its policy updates. [9] [10]

History

Chatbot Arena (2023–2024)

Chatbot Arena was released on April 24, 2023. During the first week, Vicuna (vicuna-13b), an LLM fine-tuned from LLaMA by Arena (then LMSYS) was ranked at #1, with an ELO of 1169, followed by Koala (koala-13b), a dialogue model by BAIR at #2 with an ELO of 1082, and Oasst Pythia (oasst-pythia-12b), an LLM by LAION at #3 with an ELO of 1065. [11] In the second week, GPT-4, Claude-v1, and GPT-3.5 were added to the arena alongside RWKV-4-Raven-14B. [12] The website had collected over 130,000 votes by December 2023. [13]

LMArena (2024–2026)

In September 2024, Chatbot Arena moved to its own dedicated domain name, lmarena.ai (or LMArena), [14] thus separating from LMSys. [15]

In April 2025, LMArena incorporated as an independent company. [16] That May, LMArena raised $100 million in a seed funding round, valuing the company at $600 million. [17] Participants in the seed funding round included Andreessen Horowitz, UC Investments, Lightspeed Venture Partners, Felicis Ventures, and Kleiner Perkins. [17]

On January 6, 2026, LMArena announced the closing of a $150 million Series A funding round, bringing the company’s post-money valuation to approximately $1.7 billion. The round was led by Felicis and UC Investments (University of California), with participation from Andreessen Horowitz, The House Fund, LDVP, Kleiner Perkins, Lightspeed Venture Partners, and Laude Ventures. Arena stated that the funding would be used to scale its AI evaluation platform, expand technical and research teams, and support product development following rapid community growth and adoption. [18]

Arena (2026–present)

On January 28, 2026, LMArena rebranded to "Arena". [1]

References

  1. 1 2 "LMArena is now Arena". Arena Blog. January 28, 2026. Retrieved January 28, 2026.
  2. ↑ Hart, Robert (July 18, 2024). "What AI Is The Best? Chatbot Arena Relies On Millions Of Human Votes". Forbes . Retrieved April 21, 2025.
  3. ↑ Kruppa, Miles (December 5, 2024). "The UC Berkeley Project That Is the AI Industry's Obsession". The Wall Street Journal . Retrieved April 21, 2025.
  4. ↑ Nuñez, Michael (November 15, 2024). "Google Gemini unexpectedly surges to No. 1, over OpenAI, but benchmarks don't tell the whole story". VentureBeat . Retrieved April 21, 2025.
  5. ↑ Edwards, Benj (March 27, 2024). ""The king is dead"—Claude 3 surpasses GPT-4 on Chatbot Arena for the first time". Ars Technica . Retrieved April 21, 2025.
  6. ↑ Metz, Rachel (February 18, 2025). "Before DeepSeek Blew Up, Chatbot Arena Announced Its Arrival". Bloomberg News . Retrieved April 21, 2025.
  7. ↑ Ziff, Maxwell (Aug 26, 2025). "Google Gemini's AI image model gets a 'bananas' upgrade". TechCrunch . Retrieved August 27, 2025.
  8. ↑ Langley, Hugh (Aug 19, 2025). "Is Google behind a mysterious new AI image generator? These bananas might confirm it". Business Insider . Retrieved August 27, 2025.
  9. ↑ Stokel-Walker, Chris (February 6, 2025). "Hundreds of rigged votes can skew AI model rankings on Chatbot Arena, study finds". Fast Company . Retrieved April 21, 2025.
  10. ↑ Wiggers, Kyle (September 5, 2024). "The AI industry is obsessed with Chatbot Arena, but it might not be the best benchmark". TechCrunch . Retrieved April 21, 2025.
  11. ↑ Zheng, Lianmin; Sheng, Ying; Chiang, Wei-Lin; Zhang, Hao; Gonzalez, Joseph E.; Stoica, Ion (May 3, 2023). "Chatbot Arena: Benchmarking LLMs in the Wild with Elo Ratings". LMArena Blog. Retrieved January 28, 2026.
  12. ↑ Zheng, Lianmin; Sheng, Ying; Zhang, Hao; Gonzalez, Joseph E.; Stoica, Ion (May 10, 2023). "Chatbot Arena Leaderboard Updates (Week 2)". LMArena Blog. Retrieved January 28, 2026.
  13. ↑ "Chatbot Arena: New models & Elo system update | LMSYS Org". lmsys.org. Retrieved 2026-01-30.
  14. ↑ arena.ai [@arena] (20 September 2024). "We are happy to announce a new site for Chatbot Arena!" (Tweet). Retrieved 30 January 2026– via Twitter.
  15. ↑ "Announcing a New Site for Chatbot Arena | LMSYS Org". lmsys.org. 20 September 2024. Archived from the original on 21 September 2024. Retrieved 30 January 2026.
  16. ↑ LMArena (17 April 2025). "LMArena is Growing to Support our Community Platform | LM Arena". blog.lmarena.ai. Archived from the original on 2025-05-24. Retrieved 2026-01-30.
  17. 1 2 Wiggers, Kyle (2025-05-21). "LM Arena, the organization behind popular AI leaderboards, lands $100M". TechCrunch. Archived from the original on 21 May 2025. Retrieved 30 January 2026.
  18. ↑ "Fueling the World's Most Trusted AI Evaluation Platform". LMArena Blog. 2026-01-06. Retrieved 2026-01-08.
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