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AG-UI Is Redefining the Agent–User Interaction Layer
By Nathan Tarbert
October 30, 2025

The AG-UI Protocol continues to surge - and with it, a new standard is forming across the agentic landscape.

AG-UI isn’t just another SDK or framework that has emerged. It’s an open protocol for agent <> user communication, enabling real-time collaboration between humans and agents across any app, platform, or framework.

In the simplest form, it’s the bridge between the agent and the user.

A little bit of a backstory - what started as an internal solution inside the CopilotKit ecosystem, has grown into an open-source movement - now being adopted, extended, and accelerated by large scale teams across the industry.

“The future of agents isn’t one company or one platform - it’s an agentic ecosystem connected by protocols.”

CopilotKit Team

The Protocol Triangle: MCP + A2A + AG-UI

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Agent Stack Triangle
Together, MCP, A2A, and AG-UI form what we call the Protocol Triangle that equals the new foundation of the agentic ecosystem.

Each protocol plays a unique but connected role:

  1. MCP → defines how agents communicate with tools and APIs
  2. A2A → defines how agents communicate with other agents
  3. AG-UI → defines how agents communicate with users

This triad enables a new generation of collaborative systems, where humans, agents, and applications share context, take actions, and learn together in real time.

Highlights from the Past Month

The AG-UI and CopilotKit ecosystem has been growing at an unprecedented pace. A few key milestones:

  • Google’s ADK officially joined the AG-UI ecosystem - releasing their integration and enabling ADK agents to collaborate with users via the AG-UI protocol.
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  • The “Fullstack Agents” Hackathon SF brought developers together to build with MCP, A2A, and AG-UI - showing the power of multi-agent collaboration.
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  • CopilotKit surpassed 2 million agent-user interactions per week, doubling in just two weeks.
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  • AG-UI crossed 9,000 GitHub stars ⭐️, one of the fastest-growing open-source protocol projects in the space.
  • AG-UI + CopilotKit hit 120,000 weekly installs - an explosive milestone that shows how fast developers are adopting this new protocol layer.
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Weekly installs (Oct 2024 → Sep 2025)

The Handshake 🤝 Heard Around the Ecosystem

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This month also marked the official handshake between A2A and AG-UI - connecting agent-to-agent and agent-to-user communication layers for the first time.

And two other giants 🧐 - (you’ll have to guess who they are 😁) - are now actively building their own integrations. More on that soon.

The Bigger Picture

This isn’t just about numbers. It’s about interoperability becoming inevitable.

Developers are no longer constrained by silos — they can now connect agents, apps, and humans under one shared language of interaction.

AG-UI’s rapid adoption signals something bigger:

The agentic web is becoming standardized.

What’s Next

The CopilotKit team and AG-UI community are already working on what’s next:

  • Expanding SDK support - now including TypeScript, Python, Kotlin, Java, and Golang
    • Rust (coming soon)
  • Deepening integrations across MCP and ADK
  • Designing new collaboration features that make agent-user experiences more intuitive, shared, and human

If you’re building agents, or platforms where humans and agents collaborate - AG-UI is the protocol to watch.

Explore More:

Follow CopilotKit on Twitter and say hi, and if you'd like to build something cool, join our active Discord community of agentic builders.

Happy Building!

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