Arena
Arena is a free, community-powered platform where frontier AI models answer your prompt anonymously and you vote for the better reply. Those votes build thirteen public leaderboards covering text, code, image, video, search and agents.
What is Arena?
Arena, known until recently as LMArena, is a community-powered platform for measuring how AI models perform in the real world. It was created by researchers from UC Berkeley and is operated by Arena Intelligence, Inc., a company based in the United States. Its About page describes tens of millions of builders, researchers and creative professionals using frontier models there and giving feedback on the answers they get.
The mechanism is deliberately simple. You type a prompt; in Battle Mode two anonymous models answer it; you decide which reply serves you better and vote. Only votes cast while the models are still anonymous count towards the official ranking, and the names appear the moment you have chosen. Those votes feed a Bradley-Terry rating, the statistical model built for paired comparisons and close in spirit to the Elo system used in chess. Arena publishes refinements to it, including style control, sentiment control and prompt freshness.
The result is thirteen public leaderboards: Overall, Agent, Text, WebDev, Image-to-WebDev, Text to Image, Image Edit, Text to Video, Image to Video, Video Edit, Vision, Document and Search. The Text arena alone listed 678 models in August 2026, scored across columns such as Expert, Hard Prompts, Coding, Maths, Creative Writing and Instruction Following.
Around that core sit eight use cases: chat, building apps and websites, writing and editing text, web search, image generation, video generation, picking any model directly, and side-by-side comparison. Model laboratories also supply pre-release versions under codenames, so testers often meet a model before it appears anywhere else; such a model joins the public board under its real name only if it passes both its maker's criteria and Arena's own policy.
Arena has worked this way since March 2024 and publishes its raw material: open human-preference datasets on Hugging Face, a methodology paper and a dozen conference publications. The platform is free, with no pricing page and no paid tier; the company funds itself by selling AI Evaluations to enterprises, model laboratories and developers.
What it does
- Send one prompt, receive two anonymous model answers and vote for the better one
- Compare several models you pick yourself, side by side, on the same prompt
- Talk to a single named model directly, with no voting involved
- Build web apps and websites in the Code Arena while judging the models that write them
- Generate images and videos, and rank the models that produced them
- Search the web through competing models and read thirteen public leaderboards
- Attach files to a prompt and search back through your own conversation history
When to use Arena / When not to
A quick filter to help you decide if Arena is the right fit.
When to use Arena
- Developers and engineers choosing which AI model to build on, using leaderboards broken down by coding, maths and instruction following
- AI and machine-learning researchers who need open human-preference datasets and a published evaluation methodology
- Product managers and founders who want to test frontier models on their own prompts before committing to a vendor
- Writers, designers and video creators looking for free access to leading text, image and video models in one place
- Students and curious newcomers who want to try frontier AI without a subscription, an API key or even an account
When not to use Arena
- Anyone handling confidential, client or regulated data: conversations are shared with model providers and may be published
- Teams that need a Data Processing Agreement, a named hosting region or a security certification, none of which Arena publishes
- Developers who want to call these models programmatically: there is no public API and no documentation for one
- Users under eighteen, who are excluded by both the Terms of Use and the Privacy Policy
- Organisations that require the ability to keep their data out of model improvement or public research datasets
How to use Arena
A typical end-to-end flow, from setup to results.
- Open the site in a browser: no account, no installation and no API key are needed to start
- Pick the right tool for the job, whether that is chat, code, text, web search, image or video
- Type your prompt, or click one of the suggested starters such as building a dashboard or making a game
- Attach any supporting files with the Add files control
- In Battle Mode, read both anonymous answers and compare them properly before deciding
- Vote for the reply that best fits what you actually needed
- See the two model names revealed, then continue the conversation or start a fresh one
- Expect the models to be resampled anonymously after every vote, even within the same thread
- Switch to Side by Side to choose the contenders yourself, or to Direct to talk to one named model
- Open the Leaderboard to see where each model currently stands, and log in if you want your history kept
Pros & Cons
Pros
- Free, unlimited access to frontier models from many providers, with no subscription and no API key
- Blind comparison: model names stay hidden while you vote, which limits brand bias
- A published methodology, from Bradley-Terry ratings to style and sentiment control, backed by a dozen conference papers
- Genuinely multimodal coverage: text, code, images, video, vision, documents, web search and agents
- Open human-preference datasets on Hugging Face that anyone can download and reuse
- Access to pre-release models under codenames, often before they are available anywhere else
- An Article 27 GDPR representative for the EU and UK, no targeted advertising and no significant automated decision-making
Cons
- Conversations are shared with model providers and may be published, and no opt-out is documented
- No Data Processing Agreement, no security certification and no stated hosting country or region
- No public API and no mobile app: the browser is the only way in
- Restricted to users aged eighteen and over
- Mandatory arbitration and a class-action waiver, with only thirty days to opt out
- No support email address; help comes through the help centre, Discord or the privacy inbox
- Votes cast in Side by Side and Direct modes do not count towards the public ranking, which is easy to miss
Pricing & Plans
Arena is free of charge. The site has no pricing page at all, no paid tier and therefore no entry price or billing currency to report; a free trial is not offered because nothing sits behind a paywall. The company states that it sustains itself by selling AI Evaluations to enterprises, model laboratories and developers. That service is arranged by email and its rates are not published.
- every mode
- every model and every leaderboard
- with no published quota and no commercial plan name
- a separate service for enterprises
- model laboratories and developers
- arranged by email and not publicly priced
Data, GDPR & hosting
A consolidated view of how Arena handles your data.
GDPR overview
Arena's implementation is concrete rather than declarative. The Privacy Policy, effective 16 December 2025, carries a dedicated Notice to European users covering the EEA and the United Kingdom. Arena names itself the controller for the purposes of the GDPR and sets out its legal bases: contractual necessity, legitimate interests, compliance with law and consent. It has appointed Data Protection Representative Limited, trading as DataRep, as its Article 27 representative for the European Union and the United Kingdom, reachable at arena@datarep.com. European rights are enumerated, including access, correction, erasure, portability, restriction and objection, and the policy links to the EDPB list of national supervisory authorities. No Article 37 data protection officer is named, and neither Standard Contractual Clauses nor an adequacy decision is mentioned anywhere.
Who owns the data?
Arena's Terms of Use state plainly that the company claims no ownership of anything you generate, share or upload: as between you and Arena Intelligence, Inc., you own your inputs and outputs. The licence you grant in exchange is far wider than that sentence suggests. It is non-exclusive, transferable, perpetual, irrevocable, worldwide, fully paid, royalty-free and sublicensable through multiple tiers, and it covers copying, modifying, translating, distributing, publicly displaying and deriving revenue from your content. The same clause lets Arena and the third-party providers behind the models use that content to develop and improve their services, including labelling, classification and moderation, and for marketing purposes.
Reuse rights
Because you remain the owner of your inputs and outputs, you may reuse whatever a model produces for you without asking Arena's permission. Two caveats sit in the same section of the Terms: an output may not be unique, since another user submitting a similar prompt can receive the same or a similar result, and Arena gives no warranty that outputs are protectable by intellectual property law. Additional licence conditions may also come from the third-party provider whose model answered you, and the Terms make you responsible for reviewing and complying with them. Separately, Arena publishes part of its anonymised voting data on Hugging Face for the research community: prompt text, voting outcomes and model pairings are included, full conversation logs are not.
Data retention & training
Hosting summary
Arena publishes almost nothing about where data physically sits. The Privacy Policy states that the company is headquartered in the United States and may use service providers operating in other countries, and that personal information may be transferred to the United States or to other locations whose privacy laws are less protective than your own. That is a transfer clause, not a hosting commitment: no country, region or data centre is named, and the site has no trust or security page. No transfer mechanism is cited either, with neither Standard Contractual Clauses nor an adequacy decision mentioned anywhere. The Security section promises technical, organisational and physical safeguards in general terms, with the usual caveat that no internet service can guarantee security, and no certification such as SOC 2, ISO 27001 or HIPAA is claimed. For the record, the domain resolves to a Cloudflare anycast address, which identifies a content-delivery point of presence rather than the place where anything is stored. Anyone with a data residency requirement should assume it is not met.
Where Arena works
Country-level availability.
Not available in
Things to keep in mind
Risks and trade-offs to weigh before adopting Arena.
- Anything you type may become public: the site warns, under the prompt box, not to submit information you would not want shared, and continuing to use it counts as instructing Arena to share
- The Terms grant a perpetual, irrevocable, worldwide and sublicensable licence over your content, including the right to derive revenue from it
- It is tempting to read a leaderboard position as proof of quality; it measures human preference on the prompts people happened to submit, not factual accuracy
- Answers come from third-party models and, as the site itself notes, may be inaccurate: judging which reply reads better is not the same as checking whether either is right
- Disputes go to binding arbitration under Delaware law with a class-action waiver, and the window to opt out is only thirty days
- Codenamed pre-release models can change or disappear before launch, so impressions formed on them may not survive
- Google Analytics and PostHog run on the site, and Do Not Track signals are explicitly not honoured
Setup & Integrations
Technical difficulty
There is essentially nothing to set up. Arena runs entirely in the browser, with no installation, no API key and no configuration, and you can send a first prompt and cast a first vote without creating an account; a Log In button is there if you want one. Suggested starters on the home page get you going if you are unsure what to ask. The single concept worth grasping is the difference between Battle Mode, Side by Side and Direct, since only anonymous Battle votes count towards the public leaderboards.
Deployment
Supported languages
Behind Arena
Fundraising
Social
Resources
All the official URLs gathered for verification and reference.
Frequently asked questions
Does Arena cost anything?
How are the models ranked?
Why are the models anonymous?
What are the models with codenames?
Are my conversations private?
Can I stop my data being used that way?
Is there a minimum age?
Is there an API or a mobile app?
Who is behind Arena, and how do I reach them?
Should you pick Arena?
Arena occupies an unusual position: it is one of the very few places where anyone can use the current frontier of AI, across text, code, images, video, search and agents, without paying anything or even holding an account. That access is real and generous, and the leaderboards it produces have become a reference precisely because they rest on ordinary people's preferences on ordinary prompts rather than on a fixed benchmark that laboratories can optimise against. The methodology is published, the datasets are open, and the research behind them has been through conference review.
The price is paid in privacy, and Arena is unusually direct about it. Your conversations go to the model providers and may be published; the site tells you, right under the prompt box, not to type anything you would mind seeing in public. There is no documented way to opt out, no Data Processing Agreement, no stated hosting country and no security certification. The Terms grant a perpetual, irrevocable, worldwide and sublicensable licence over what you submit, including the right to earn revenue from it, even while confirming that you remain its owner.
That trade is entirely reasonable for a public prompt, a coding experiment or a curiosity about which video model is currently ahead. It is the wrong trade for client work, personal matters or anything covered by a confidentiality obligation. Read the leaderboards as a measure of human preference rather than of factual accuracy, and remember that votes cast outside Battle Mode do not move them.
Used with that in mind, Arena is the fastest honest answer to the question every builder now asks: which model should I use for this? Very few free tools earn that description.
- Choosing a selection results in a full page refresh.
- Opens in a new window.