head to head · open source
Open WebUI vs Kai
Open WebUI has 152,426 GitHub stars, 22,301 forks, 294 open issues and last shipped today. Kai has 1,253 stars, 182 forks, 127 open issues and last shipped 2 days ago. Open WebUI leads on adoption by 12,065% (152,426 vs 1,253 stars). Open WebUI is written in Python under a custom or non-standard licence; Kai is written in Kotlin under Apache-2.0. Open WebUI has attracted 15% as many forks as stars, Kai 15%. Open WebUI was the more recently maintained of the two, and both are self-hostable with no licence fee. The two share 1 topic tag (ai), so they are genuine substitutes rather than adjacent tools.
Two open source projects, one decision. Both are free and self-hostable — the differences are community size, license terms, language stack and release pace.
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Side by side
| Open WebUI | Kai | |
|---|---|---|
| GitHub stars | ★ 152K | ★ 1.3K |
| License | Custom / other | Apache-2.0 |
| Written in | Python | Kotlin |
| Last push | 2026-09-18 | 2026-09-16 |
| Forks | ⑂ 22K | ⑂ 182 |
| Self-hosting | Yes | Yes |
| Data ownership | Your server | Your server |
pick Open WebUI if
- You weight community size — 152K stars and counting
- You want the Custom / other license terms
- Your stack matches Python
- You value the larger contributor base for long-term maintenance
pick Kai if
- You want the Kai feature set and don't need the biggest community
- You prefer the Apache-2.0 license terms
- Your stack matches Kotlin
- You evaluated both and Kai fits your workflow better
About Open WebUI
Open WebUI is a self hosted, open source AI interface that unifies access to local and cloud based large language models. It runs entirely in a web browser and supports Ollama for local model hosting alongside any OpenAI compatible API, including services like LMStudio, GroqCloud, Mistral, and OpenRouter. Built in Python, it functions as a drop in replacement for proprietary AI platforms, giving users full control over their model infrastructure and data.
read the full Open WebUI overview →
About Kai
Kai 9000 An open source AI assistant with persistent memory that runs on Android, iOS, Windows, Mac, Linux, and Web . Website Documentation Sponsor: Atlas Cloud Installation Homebrew (macOS): AUR (Arch Linux): Winget (Windows): Direct Downloads AI That Builds Screens, Not Just Text Kai 9000's Interactive UI lets the AI generate full interactive screens — quizzes, dashboards, recipes, brainstorms, and more. Navigate by tapping buttons instead of scrolling through chat. Features Persistent memory — Kai remembers important details across conversations and uses them automatically Customizable soul — Define the AI's p…
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Frequently asked questions
Is Open WebUI or Kai more popular?
Open WebUI has 152,426 GitHub stars and Kai has 1,253. Open WebUI has the larger community by that measure.
Are Open WebUI and Kai free?
Both are open source. Open WebUI has no licence declared in this registry, and Kai is licensed under Apache-2.0. Both are free to self-host.
What is the difference between Open WebUI and Kai?
Open WebUI is written in Python and Kai in Kotlin. The practical differences are community size, licence terms, language stack and release cadence — all compared in the table above.
Which should I choose, Open WebUI or Kai?
Choose Open WebUI if you want the larger community (152,426 stars) or its Custom / other licence terms. Choose Kai if its feature set, stack or Apache-2.0 licence fits better. Both are self-hostable.