LMArena vs Open WebUI
Which should you use? A side-by-side look at what each one does, who it suits, what it costs, how hard it is to set up, and where each falls short.
AI tool · Free
A public arena where you prompt two anonymous models side by side and vote, producing crowd-sourced leaderboards.
AI tool · Open source
A self-hosted chat interface for local and API models with saved prompts, document chat and a community library.
Our verdict
LMArena and Open WebUI serve different purposes, so they are not really rivals. LMArena is a free public website where you send one prompt to two anonymous models, vote for the better answer, and see crowd-sourced leaderboards. Open WebUI is a self-hosted chat interface you run yourself for local and API models, with saved prompts, document chat and a community library. Choose based on whether you want to compare models or want a daily chat tool you control.
Pick LMArena if you want a quick, free, blind comparison of models or want to check how public leaderboards rank them.
Pick Open WebUI if you want a private, self-hosted chat interface for local or API models, with saved prompts and document chat.
| Key difference | LMArena | Open WebUI |
|---|---|---|
| Main purpose | Blind side-by-side voting between two anonymous models | Self-hosted chat interface for daily model use |
| Price | Free | Open source; you pay for your own hosting |
| Setup | None; use it in a web browser | You install and maintain it yourself on your own machine or server |
| Model support | Public arena models chosen by the site | Works with Ollama and API models |
| Best at | Crowd-sourced leaderboards across text, vision and coding | Saved prompts, document chat and running local models |
Written with AI from both products' catalogue entries · updated 2026-10-29
Who each one is for
Choose LMArena if you need…
- Blind model comparisons
- Checking model leaderboards
Choose Open WebUI if you need…
- Running local models with a nice UI
- Self-hosted team chat
Side-by-side
| LMArena | Open WebUI | |
|---|---|---|
| Type | Prompting · Prompt playgrounds | Prompting · Prompt playgrounds |
| Price | Free | Open source |
| Platforms | Web | Self-hosted, Web, Linux |
| Works with | — | Ollama |
| Hands-on tested by us | Not yet | Not yet |
| Last checked | 2026-10-29 | 2026-10-29 |
What each one is
LMArena
A public arena where you prompt two anonymous models side by side and vote, producing crowd-sourced leaderboards. A fun, quick sanity check across models. Leaderboards reflect crowd preference, not your specific task.
Open WebUI
A self-hosted chat interface for local and API models with saved prompts, document chat and a community library. Feature-rich and private when self-hosted. Setup and updates are on you, and the licence has branding conditions.
Best for
LMArena
- Blind model comparisons
- Checking model leaderboards
Open WebUI
- Running local models with a nice UI
- Self-hosted team chat
Strengths
LMArena
- Side-by-side anonymous battles
- Public leaderboards
- Text, vision and coding arenas
Open WebUI
- Ollama and API model support
- Saved prompts and models
- Document RAG
- Community prompt sharing
Frequently asked questions
Should I use LMArena or Open WebUI?
LMArena and Open WebUI serve different purposes, so they are not really rivals. LMArena is a free public website where you send one prompt to two anonymous models, vote for the better answer, and see crowd-sourced leaderboards. Open WebUI is a self-hosted chat interface you run yourself for local and API models, with saved prompts, document chat and a community library. Choose based on whether you want to compare models or want a daily chat tool you control. Pick LMArena if you want a quick, free, blind comparison of models or want to check how public leaderboards rank them. Pick Open WebUI if you want a private, self-hosted chat interface for local or API models, with saved prompts and document chat.
What is the difference between LMArena and Open WebUI?
LMArena: A public arena where you prompt two anonymous models side by side and vote, producing crowd-sourced leaderboards. Open WebUI: A self-hosted chat interface for local and API models with saved prompts, document chat and a community library. LMArena suits blind model comparisons, while Open WebUI suits running local models with a nice ui.
Are LMArena and Open WebUI free?
LMArena: Free. Open WebUI: Open source.
What are other alternatives to LMArena and Open WebUI?
Other options people compare them with include Claude Console, Google AI Studio, OpenRouter, OpenAI Playground, TypingMind.
Keep comparing
Built from our catalogue entries for both products: open-source details come from each project's README (AI-assisted, refreshed weekly) and GitHub data; AI-tool details are editorial. Spotted something wrong? Let us know from either product's page.