The archive · Developer & Business Tools · Strategic decision · 2023–2026
CopilotKit bets an open agent-to-user protocol, not chat, wins the agent era
Seattle startup's AG-UI protocol is adopted by Google, Microsoft, Amazon and Oracle; a $27M Series A follows in May 2026.
CopilotKit
What the business is
CopilotKit is a Seattle open-source startup building the connection layer between AI agents and user-facing apps: the CopilotKit framework plus AG-UI, an open event-based protocol for streaming text, state and tool calls from an agent backend into interactive UIs.
Starting capital：$27M Series A led by Glilot Capital, NFX and SignalFire, announced 2026-05-05 (TechCrunch).
How it started
Co-founders Atai Barkai (CEO) and Uli Barkai (head of growth) built CopilotKit in Seattle as open-source infrastructure so developers could put AI agents inside their own products instead of bolting on a chat window. The framework's internal agent-to-UI plumbing was extracted and launched in May 2025 as AG-UI, an open, event-based protocol over SSE or WebSockets, deliberately positioned next to Anthropic's MCP (agents to tools) and Google's A2A (agents to agents) as the agent-to-user leg of the stack.
What happened
The protocol gained ground through 2025 — Runa's ROSS Index logged about 5.8k repo stars by August 2025. On May 5, 2026 CopilotKit announced a $27M Series A led by Glilot Capital, NFX and SignalFire, launched CopilotKit Enterprise Intelligence (a self-hostable enterprise layer), and said AG-UI was supported by Google, Microsoft, Amazon and Oracle plus frameworks LangChain, Mastra, PydanticAI and Agno; TechCrunch and ynet reported 40,000+ GitHub stars across its repos and millions of weekly installs.
How it ended up
Live and scaling: the May 2026 Series A funds an enterprise layer built on an open protocol; CopilotKit counts Deutsche Telekom, Docusign, Cisco and S&P Global as customers and says a majority of the Fortune 500 uses its tools in production.
Background
CopilotKit is a Seattle open-source startup, co-founded by Atai Barkai and Uli Barkai, that builds the plumbing for putting AI agents inside the applications people actually use. Its premise: agents do not behave like traditional software — they stream, wait, resume and collaborate with humans — so the old chat-box pattern for AI products has to be replaced by an interaction layer between agent backends and user interfaces.
The company's key move was AG-UI (Agent-User Interaction), an open, MIT-licensed, event-based protocol that standardizes how an agent connects to a frontend: typed events for streaming text, shared state, tool calls and human-in-the-loop interrupts over SSE or WebSockets. AG-UI emerged from CopilotKit's work with LangGraph and CrewAI and launched in May 2025, positioned next to MCP (agent-to-tools) and A2A (agent-to-agent) as the agent-to-user leg of the stack.
Adoption grew fast enough to draw in the platforms themselves. Runa's ROSS Index logged about 5.8k AG-UI stars by August 2025, and when CopilotKit announced a $27M Series A led by Glilot Capital, NFX and SignalFire on May 5, 2026 — alongside a self-hostable enterprise product — AG-UI was supported by Google, Microsoft, Amazon and Oracle and frameworks including LangChain, Mastra, PydanticAI and Agno. TechCrunch and ynet reported 40,000+ GitHub stars across CopilotKit's repos and millions of weekly installs.
As of September 2026 AG-UI holds roughly 15.7k GitHub stars, having reached a best daily GitHub-trending rank of #17 on July 29, 2026. CopilotKit reports more than 40,000 GitHub stars across its repositories, millions of weekly installs, and customers including Deutsche Telekom, Docusign, Cisco and S&P Global. Its stated strategy is to keep the open protocol neutral and monetize enterprises that want self-hosting and support.
What has to be true
- Open standard over vendor SDK: by making AG-UI a neutral MIT-licensed protocol, CopilotKit let competitors and cloud giants integrate it, which no single company's proprietary SDK could achieve.
- It rode the protocol wave: MCP and A2A had already legitimized agent protocols, so AG-UI only had to own the one leg they missed — the connection between agents and users.
- Bottom-up adoption preceded enterprise sales: 9,000 stars and 120,000 weekly installs arrived before the Series A, so funding and enterprise tooling came as a response to developer pull.
- Monetization matches the open layer: the paid product hardens and self-hosts the same open stack instead of forking it, keeping the standard neutral for developers who never pay.
What can be applied
To become infrastructure, make the protocol the product: an open standard that cloud providers integrate on their own beats a proprietary SDK with the same features.
Aftermath
As of September 2, 2026, CopilotKit is scaling on its open-protocol bet: AG-UI holds 15.7k GitHub stars (best trending rank #17 on July 29, 2026), is adopted by Google, Microsoft, Amazon and Oracle and leading agent frameworks, and its repos carry 40,000+ stars with millions of weekly installs. The $27M Series A (May 2026) funds CopilotKit Enterprise Intelligence, a self-hostable layer for in-app agents, with Deutsche Telekom, Docusign, Cisco and S&P Global as named customers. The open question is whether it can stay a neutral standard while selling enterprise products on top of it.
Sources
- CopilotKit raises $27M to help devs deploy app-native AI agents
- CopilotKit raises $27 million to build the interface layer between humans and AI agents
- What is AG-UI? The Agent-User Interaction protocol
- Top trending open-source startups in Q3 2025 (ROSS Index)
- ag-ui-protocol/ag-ui star history
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