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A2UI

Google
open source / Overall score: 4.0(strong)

A2UI (Agent-to-User Interface) is an open protocol that lets an AI agent describe an interface as declarative JSON, which the client draws from its own catalog of trusted components instead of running code the agent wrote. Its repository holds the specification, renderers for Lit, Angular and React, and agent SDKs for Python and Dart, and messages travel over A2A or AG-UI. Google created it, with contributions from CopilotKit.

Read against a2ui-project/a2ui, the home the project site, the contributing guide and every package's metadata now name; the older google/A2UI path serves the same tree. Two packages are declared: the shared web core that every A2UI web renderer installs, and the Python agent SDK. The renderer packages and a2ui-core are left undeclared because each depends on, or is a dependency of, one of those two.

Openness

5 high confidence
5.0
license
Apache-2.0(OSI
source
public(the specification, the renderers and the agent SDKs, with every published package built from this repository)
core features withheld
no — the tree at cbaa5ee carries one root Apache-2.0 LICENSE and no ee/, enterprise/, commercial/ or proprietary/ path

A2UI is Apache-2.0 licensed, and its public repository holds the specification together with the renderers and agent SDKs published to npm and PyPI, so everything people install builds from published source. Nothing is kept back for a paid edition, and the project site presents it only as an open project Google created with contributions from CopilotKit and the wider community.

  • https://a2ui.org recorded 2026-10-19

    The project site says "A2UI is Apache 2.0 licensed, created by Google with contributions from" CopilotKit "and the open source community," and links github.com/a2ui-project/a2ui as where it is in active development. Searched the body for pricing, paid, enterprise and commercial, and found none of them.

  • https://raw.githubusercontent.com/a2ui-project/a2ui/main/LICENSE recorded 2026-10-19

    The root LICENSE is the Apache License text, headed "Apache License" and "Version 2.0, January 2004", followed by a notice that "The file eval/bin/transcrypt is licensed under the MIT License".

  • https://raw.githubusercontent.com/a2ui-project/a2ui/main/README.md recorded 2026-10-19

    The README opens "A2UI is an open-source project, complete with a format optimized for representing updatable agent-generated UIs and an initial set of renderers". Its Packages section says "These packages are developed in this repository" and lists a2ui-core and a2ui-agent-sdk on PyPI, @a2ui/web_core, @a2ui/lit, @a2ui/angular, @a2ui/react and @a2ui/markdown-it on npm, and Dart packages on pub.dev, and it closes by calling A2UI an Apache 2.0 licensed project. Searched the body for pricing, paid, subscription, license key, premium, hosted and commercial, and found none of them.

  • https://registry.npmjs.org/@a2ui/web_core/latest recorded 2026-10-19

    The npm record for @a2ui/web_core 0.14.0 declares the Apache-2.0 license, author Google, and the repository "git+https://github.com/a2ui-project/a2ui.git" with directory "typescript/core/web_core". Every dependency it lists is a public npm package.

Adoption

4 medium confidence
4.0

Adoption is the trailing month of npm downloads of @a2ui/web_core, which every A2UI web renderer installs, plus PyPI downloads of a2ui-agent-sdk, the Python agent SDK. Part of the npm count comes from CopilotKit, whose React package installs the web core whether or not an app draws A2UI, while the Dart packages on pub.dev are not counted at all; neither changes the reading.

Capability

not assessed

A2UI is a specification for how an agent describes an interface, shipped with renderers and SDKs that implement it, so like AG-UI and the Agent2Agent Protocol it has nothing to be measured against. Neither the repository README nor the project site publishes a benchmark, leaderboard or performance figure for the protocol.

  • https://a2ui.org recorded 2026-10-19

    The project site calls A2UI "A Protocol for Agent-Driven Interfaces" and lists its specification versions as v1.0 candidate, v0.9.1 current, v0.9 stable and v0.8 legacy. Searched the body for benchmark, leaderboard and performance, and found none of them.

  • https://raw.githubusercontent.com/a2ui-project/a2ui/main/README.md recorded 2026-10-19

    The README says A2UI "is an open standard and set of libraries that allows agents to" speak UI: "Agents send a declarative JSON format describing the" intent of the UI, and "The client application then renders this using its own native component library". It names A2A and AG-UI as transports. Searched the body for benchmark, leaderboard, latency, throughput and performance, and found none of them.

Verified 2026-10-19, except some scores, still awaiting re-confirmation