Skip to content
Concepts Components Blog Roadmap
Get Started
/ A2UI Team

Google Vertex AI Integrates A2UI: The New Standard for Enterprise Agentic Interfaces

Google Cloud officially integrates A2UI into Vertex AI Agent Builder. Discover why this declarative protocol is becoming the backbone of secure, generative UI for financial services and enterprise agents.

December 24, 2025 — The landscape of Agentic AI has shifted. With the latest update to Google Cloud’s Vertex AI Agent Builder on December 23, 2025, the A2UI (Agent-to-User Interface) protocol has graduated from an experimental open-source project to a core component of the enterprise AI stack.

This integration signals a decisive move by Google to standardize how Large Language Models (LLMs) render user interfaces, specifically addressing the critical “last mile” problem of Generative UI: Security and Determinism.

The Milestone: A2UI in Vertex AI Agent Builder

In the December 23rd announcement, Google introduced enhanced governance tools and the Agent Designer within Vertex AI. Quietly but significantly, A2UI was highlighted as the supported toolkit for building “remote agent UIs.”

This endorsement transforms A2UI from a developer preference into an industry standard. For enterprise architects and CTOs, this means:

  1. Native Integration: A2UI’s JSON-based declarative schema is now natively understood by Vertex AI’s orchestration layer.
  2. Governance Ready: Unlike generating raw React or HTML code—which poses significant XSS and injection risks—A2UI’s strict schema ensures that agents can only render pre-approved, safe UI components.
  3. Cross-Platform Consistency: The same agent logic built in Vertex AI can now drive interfaces across Web, iOS, and Android without platform-specific code generation.

Why Financial Services Are Leading the Adoption

Our telemetry and recent industry reports indicate a massive surge in A2UI adoption within the Financial Services sector over the last 48 hours. Why is Finance the beachhead for this technology?

1. The “No-Code-Execution” Mandate

Banks and Fintechs operate under strict regulatory environments (GDPR, PCI-DSS, SOC2). The traditional approach to Generative UI—where an LLM outputs Javascript/HTML to be rendered by the browser—is a non-starter due to security compliance.

A2UI solves this by decoupling intent from execution. The Agent sends a JSON object describing what to render (e.g., { type: "InvestmentChart", data: [...] }), not how to execute it. The client application (the mobile banking app) retains full control over the rendering implementation.

2. Dynamic Compliance & KYC

Consider a “Smart Mortgage Agent.” Depending on the user’s jurisdiction and risk profile, the Know Your Customer (KYC) form needs to change dynamically.

  • Before A2UI: Developers hard-coded hundreds of form permutations.
  • With A2UI: The Agent dynamically constructs the form structure based on real-time regulatory checks. If a user reveals they have foreign assets, the Agent immediately injects the specific tax declaration fields into the UI stream—all strictly typed and validated by the A2UI schema.

3. Real-time Wealth Visualization

Integration with Vertex AI allows agents to pull real-time market data and stream it directly into A2UI components. An investment advisor bot can now do more than talk about a portfolio rebalance; it can instantly render an interactive “Before vs. After” allocation chart, generated on the fly.

“A2UI provides the missing link for regulated industries: the flexibility of GenAI with the safety guarantees of a static application.”

Deep Dive: The Architecture of Trust

The integration into Vertex AI relies on the synergy between A2A (Agent-to-Agent) and A2UI protocols.

  • Logic Layer (Vertex AI): The rigorous reasoning engine handles intent, grounding, and tool calling.
  • Presentation Layer (A2UI): The declarative output layer.

When a user asks, “Help me dispute this transaction,” the Vertex AI agent:

  1. Reasons: Identifies the transaction and dispute policy.
  2. Acts: Calls the banking API to freeze the card (if requested).
  3. Presents: Emits an A2UI payload: 
    {
  "type": "DisputeFlow",
  "props": {
    "transactionId": "TXN-12345",
    "recommendedAction": "freeze_card",
    "steps": ["Reason", "Evidence", "Submit"]
  }
}

The banking app receives this JSON and renders its native, distinctively branded Dispute Review screen. The AI never touched the pixels, ensuring brand consistency and UI performance.

Looking Ahead: 2026 and Beyond

With Google’s backing, we expect the ecosystem around A2UI to explode in Q1 2026.

  • React & Flutter Renderers: Official libraries are stabilizing (see our Roadmap).
  • Design System Bridges: Tools to automatically map Figma design systems to A2UI component registries.

The era of “Chat-only” agents is ending. The era of Agentic Applications—powered by Vertex AI and A2UI—has just began.

Stay tuned for our upcoming tutorial: “Building a Compliant Fintech Agent with Vertex AI and A2UI”.

Back to Blog