OpenUI vs others
OpenUI vs json-render (Vercel), A2UI (Google), and CopilotKit OpenGenerativeUI.
Open-source Generative UI projects share a common goal: enabling agents to respond with interactive interfaces instead of only text. They differ in what the model generates, how applications control the available UI, and where the result can be rendered.
This page compares OpenUI with json-render, A2UI, and OpenGenerativeUI. These projects do not all solve the same part of the Generative UI stack, so the comparison focuses on their approach and intended use.
Generative UI frameworks
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OpenUI uses a compact, line-based language designed for models to generate interfaces from registered components. Its runtime supports streamed rendering, application state, data access, and user interactions.
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json-render uses streaming JSONL patches generated from a component catalog.
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A2UI is a protocol for sending declarative interface descriptions from agents to client applications. The client maps those descriptions to trusted, platform-native components.
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OpenGenerativeUI focuses on open-ended visual experiences built with CopilotKit. It supports registered React components and free-form HTML or SVG rendered inside sandboxed iframes.
Feature comparison
| OpenUI | json-render (Vercel) | A2UI (Google) | CopilotKit OpenGenUI | |
|---|---|---|---|---|
| Tokens | 1x | 3x | 3x | 4x |
| Latency (60 tok/s) | 4.9s | 14.2s | 14.2s | ~20s |
| Streaming | Yes | Yes | Yes | Partial |
| Consistent output | Yes | Yes | Yes | No |
| Design system | Yes | Yes | Yes | No |
| Components | Library + custom | Library + custom | Custom only | None |
| Built-in data fetching | Yes | No | No | No |
| Chat UI included | Yes | No | No | Yes |
| Multi-platform | Web, mobile, email | Web, mobile, PDF, email, video | Web, iOS, Android | Web |
| Security risk | Minimal | Minimal | Minimal | Medium |
| License | MIT | Apache 2.0 | Apache 2.0 | MIT |
Choosing a framework
- Data-driven chat UIs and dashboards → OpenUI
- One UI across web, mobile, PDF and email → OpenUI
- Multi-agent systems across iOS, Android, and web → OpenUI
- Creative one-off visuals (animations, generative art) → CopilotKit OpenGenUI