A2UI

Declarative JSON, not executable code

Agents describe intent as data: structure, components, props, and bindings arrive as JSON messages that the host app renders with its own trusted component library. No arbitrary code executes from the agent, reducing XSS/RCE risk and keeping styling consistent. Because UIs are data, they can be diffed, replayed, logged, versioned, and audited—useful when assistants operate across accounts, tenants, or regulated workflows where provenance matters as much as speed.

Cross-platform native renderers

Client libraries render the same A2UI JSON into native surfaces for the web (e.g., Angular/Lit), mobile (Flutter), and desktop. Hosts control theming and accessibility while agents focus on task logic. This separation lets one agent interface travel anywhere your product does—support chat, sidebars, and full-screen apps—without re-authoring UI code. Teams ship consistent, brand-aligned experiences for many platforms from a single protocol instead of bespoke UI per client.

Streaming updates & data binding

A2UI streams UI changes over time, so assistants can add steps, refine forms, and update results live as plans evolve. A distinct data model enables reactive updates: inputs flow back to the agent; state changes re-render without full refreshes. Developers get predictable lifecycles for mount/update/unmount and clear contracts for events. The result is conversational software with the responsiveness of native apps—great for iterative tools like planners, search, and configurators.

Security, trust & governance

Because agents send data, not code, hosts enforce permissions, sandboxing, and design rules. Components whitelist allowed inputs; transports control who can speak; logs preserve every message for review. This model helps enterprises adopt agentic UX without surrendering brand or security posture. It also simplifies threat modeling across third-party or remote agents, letting security teams reason about surfaces as structured messages instead of opaque script blobs.

Open source, ecosystem & quickstart

Released under Apache-2.0, A2UI invites community renderers, transports, and components. Quickstart demos (e.g., a restaurant finder) get teams hands-on in minutes, while docs cover concepts, lifecycles, theming, and custom widgets. Active GitHub issues/discussions track naming, schema polish, and new client libraries. The outcome is a shared foundation others can extend—avoiding duplicative “agent UI” efforts and accelerating interoperable tools across vendors and stacks.