Arena (formerly Chatbot Arena)

What it is

Spec sheet

What it does

Arena lets people compare anonymous AI-model responses, vote for the better answer, and contribute to public rankings.Read 21 Oct 2026 · arena.ai

Product

Arena is an AI evaluation platform where users compare model responses and vote to shape public leaderboards.Read 7 Oct 2026 · arena.ai

API

Arena provides an OpenAI-compatible gateway with model listing and chat-completion endpoints authenticated by virtual API keys.Read 21 Oct 2026 · portal.api.preview.arena.ai

Privacy

Arena says conversations may be used for research datasets and private model-provider evaluations, and shared data is de-identified; it advises users not to submit sensitive information.Read 7 Oct 2026 · arena.ai

Founded

2023Read 28 Sep 2026 · arena.ai

Account benefits

Creating an account unlocks Direct, Side-by-Side, Image, and Video modes, higher rate limits, and synchronized chat history.Read 21 Oct 2026 · help.arena.ai

Account integrations

Users can create an account with Google or email, and Arena’s coding Agent Mode can connect to GitHub repositories.Read 7 Oct 2026 · help.arena.ai

Account requirements

Leaderboards can be viewed without signing in, while Direct, Side by Side, Image Arena, and Video Arena require login.Read 7 Oct 2026 · help.arena.ai

Age restriction

The privacy policy says the service is not intended for people under 18.Read 21 Oct 2026 · help.arena.ai

Agent files

Agent Mode accepts PNG, WebP, JPEG, PDF, GIF, TXT, Markdown, CSV, HTML, XML, CSS, JavaScript, and JSON uploads.Read 21 Oct 2026 · help.arena.ai

Agent mode

Agent Mode plans multi-step work and can use web search, image generation, file uploads, coding assistance, and a sandbox/bash environment.Read 21 Oct 2026 · help.arena.ai

Anonymous battles

In Battle mode, Arena presents two anonymous model responses and reveals their identities after the user votes.Read 7 Oct 2026 · arena.ai

API compatibility

The API documentation shows Anthropic-compatible client configuration for Claude Code through the Arena API base URL.Read 21 Oct 2026 · portal.api.preview.arena.ai

Battle mode

Users submit a prompt, receive two anonymous model answers, vote, and then see the model identities.Read 21 Oct 2026 · arena.ai

Commercial customers

Arena offers commercial evaluation services to enterprises, model labs, and developers, with evaluation results supported by service-level agreements.Read 7 Oct 2026 · arena.ai

Company origin

Arena says it was created by UC Berkeley researchers and that Arena Intelligence Inc. was formed in 2025.Read 7 Oct 2026 · arena.ai

Data sharing

Arena says conversations may be de-identified and shared in public research datasets or private evaluations with model providers.Read 21 Oct 2026 · arena.ai

Developer documentation

The public API reference identifies itself as OpenAPI 3.0.3 and includes curl quickstarts.Read 21 Oct 2026 · portal.api.preview.arena.ai

Discord

The terms cover an Arena Discord server and an Arena Discord Bot as part of the service.Read 21 Oct 2026 · help.arena.ai

Funding

Arena says it has $250 million in venture funding led by Felicis and UC Investments, with participation from several other investors.Read 21 Oct 2026 · arena.ai

GitHub integration

When a GitHub repository is connected, Agent Mode works in a copy, commits changes to a branch, and opens a pull request.Read 21 Oct 2026 · help.arena.ai

Independent research result

The Chatbot Arena paper reports more than 240,000 votes and says crowdsourced questions were diverse and human votes agreed well with expert ratings.Read 21 Oct 2026 · arxiv.org

Licence status

The LMSYS project describes the FastChat platform, including its UI, serving backend, evaluation, and ranking pipelines, as open source and runnable by others.Read 21 Oct 2026 · lmsys.org

Limit: benchmark gaming

Contrary Research reports that labs deliberately target Arena and that self-selected, unpaid voters and test-set exposure can make results gameable.Read 21 Oct 2026 · research.contrary.com

Limit: directory-only review

Aigregator says the similarly named listing is mainly a discovery and reference tool, requires visiting builders for hands-on testing, and may contain outdated comparison data.Read 21 Oct 2026 · aigregator.com

Limit: model mismatch

Contrary Research describes the 2025 Llama 4 Maverick episode in which a tuned Arena variant ranked highly while the publicly released model ranked much lower.Read 21 Oct 2026 · research.contrary.com

Limit: outages

A Russian outage monitor records historical LMArena complaints involving site access, app access, photo loading, and home-network availability.Read 21 Oct 2026 · webpinger.ru

Limit: user-reported errors

Reddit users reported Agent Mode loading failures, response errors, missing history, and unusable sessions in October 2026.Read 21 Oct 2026 · reddit.com

Maker founding

Arena says it was created by UC Berkeley researchers and that Arena Intelligence Inc. was formed in 2025.Read 21 Oct 2026 · arena.ai

Maker headquarters

LinkedIn lists Arena in San Francisco, California.Read 21 Oct 2026 · linkedin.com

Maker legal name

The company identifies itself as Arena Intelligence Inc.Read 21 Oct 2026 · arena.ai

Maker size

LinkedIn lists the company size as 51–200 employees.Read 21 Oct 2026 · linkedin.com

Model arenas

Arena lists rankings for agent, text, web development, image, video, vision, document, and search tasks.Read 7 Oct 2026 · arena.ai

Modes

The platform offers Battle, Side by Side, and Direct modes; only anonymous Battle votes count toward official rankings.Read 7 Oct 2026 · arena.ai

Multimedia features

Arena supports comparing models for image generation, image editing, and video generation, among other tasks.Read 7 Oct 2026 · arena.ai

Notable news: Agent Max

Arena’s leaderboard page dates the announcement of Max in Agent Arena to October 12, 2026.Read 21 Oct 2026 · arena.ai

Notable news: Series B

Arena’s leaderboard page dates its $200 million Series B announcement to October 8, 2026.Read 21 Oct 2026 · arena.ai

Praise: breadth

An independent directory highlights anonymous head-to-head battles, public rankings, multiple evaluation categories, open datasets, and published research.Read 21 Oct 2026 · aigregator.com

Praise: open evaluation

Independent research characterizes Arena as an open, community-driven evaluation platform that became a widely referenced LLM leaderboard.Read 21 Oct 2026 · arxiv.org

Privacy warning

The FAQ advises users not to include sensitive information in conversations.Read 21 Oct 2026 · arena.ai

Ranking method

Battle votes are converted into ratings with the Bradley-Terry statistical model, similar to Elo.Read 21 Oct 2026 · arena.ai

Rating on Aigregator

0.0 out of 5 from 0 reviewsRead 21 Oct 2026 · aigregator.com

Research datasets

Arena says it has open-sourced a large repository of organic human-preference data and provides free public datasets.Read 21 Oct 2026 · arena.ai

Security and compliance

Arena’s Trust Center lists CCPA, GDPR, and NIST CSF materials and describes security, privacy, and compliance information for customer reviews.Read 7 Oct 2026 · trust.arena.ai

Security statement

Arena says it uses technical, organizational, and physical safeguards but cannot guarantee information security.Read 21 Oct 2026 · help.arena.ai

Usage limit

Arena applies a daily usage limit to all users, and usage automatically resets 24 hours after the limit is reached.Read 7 Oct 2026 · help.arena.ai

Use cases

The service supports AI chat, app and website building, writing, web search, image generation, video generation, model selection, and side-by-side comparison.Read 21 Oct 2026 · arena.ai

Video limit

Video Arena requires login, allows two generations per 24-hour period, and supports Battle mode only.Read 7 Oct 2026 · help.arena.ai

Plans and prices

Every Arena (formerly Chatbot Arena) plan and price →

Strong points and limits

Who it suits

Verdict

Where Specifiction places it

• LLM Evaluation Tools#3 of 298.8