News / Software, Web & Apps
Microsoft Releases a .NET SDK for the AG-UI Agent-User Interaction Protocol Published on 27 September 2026 by Christ-loisele (3 min read)
On September 25, 2026, Microsoft launched a software development kit (SDK) for .NET dedicated to the AG-UI protocol, standardizing exchanges between conversational agents and applications. Five NuGet packages now allow C# developers to integrate these features into their projects under the MIT license.
An Event-Based Protocol to Modernize Agent-User Interactions
The AG-UI (Agent-User Interaction) protocol marks a departure from the traditional request-response model by introducing a system based on typed events , according to Microsoft. Unlike classic synchronous exchanges, AG-UI enables agents to dynamically notify states such as the start of an execution (RUN_STARTED), the sending of textual messages (TEXT_MESSAGE_CONTENT), or state updates (STATE_DELTA). This approach, documented in the official .NET blog , facilitates interoperability between agents written in Python, TypeScript, or C# and .NET backend applications.
The SDK covers eight event categories: lifecycle, textual messages, tool calls, state management, activities, sub-agents, special events, and drafts. These categories are implemented through five distinct NuGet packages: AGUI.Abstractions (protocol types and JSON serialization), AGUI.Formatting (event stream formatting, including Server-Sent Events support), AGUI.Protobuf (optional binary encoding), AGUI.Client (HTTP client with integration to IChatClient), and AGUI.Server (adapter to transform ChatResponseUpdate streams into AG-UI events).
AG-UI standardizes how agents communicate with user applications through typed events, freeing developers from the rigid request-response model.
Photo: Microsoft (Coolcaesar, CC BY-SA 4.0) Native Integration Within the Microsoft Ecosystem and Beyond
The .NET SDK for AG-UI , developed in collaboration with CopilotKit , becomes the technical foundation for AG-UI support in the Microsoft Agent Framework (MAF) . According to Microsoft, this update now allows C# developers to create AG-UI endpoints compatible with any agent adhering to the protocol, whether written in Python, TypeScript, or C#. The SDK is published under the MIT license, ensuring flexible adoption in open-source or proprietary projects.
The SDK’s bidirectional architecture relies on two key components: AGUI.Server, which transforms an agent into an AG-UI endpoint, and AGUI.Client, enabling a .NET application to consume events emitted by an agent. For example, an ASP.NET Core backend can emit native AG-UI events while allowing flexibility in transport format (defaulting to Server-Sent Events or using protobuf for binary optimization).
What This Changes Here
For Beninese or West African companies developing virtual assistance solutions, business chatbots, or agent-based automation, this SDK offers concrete opportunities. Integrating AG-UI into .NET could simplify the connection between local backends (such as internal APIs written in C#) and third-party agents , whether hosted on international cloud platforms or local infrastructure. Public administrations, such as those managing online services (civil status, tax declarations), could thus standardize their exchanges with conversational agents without relying on proprietary solutions.
Additionally, compatibility with existing TypeScript and Python SDKs expands technological choices for mixed teams. For example, a cotton-growing SME already using Python agents for customer support could gradually migrate its infrastructure to .NET while maintaining compatibility with existing tools. Finally, the MIT license reduces legal barriers to adoption, a crucial factor in contexts where IT budgets are often limited.
Concrete examples and resources to get started
The official AG-UI GitHub repository offers ready-to-use examples covering varied use cases: conversation management (chat), tool calls (tools), shared state, multimodal input, interruptions, or parallel tool calls. These examples, compatible with the .NET SDK, enable developers to quickly test scenarios such as an agent assisting a user in an administrative procedure or a personalized recommendation system.
For specific questions about integration with the Microsoft Agent Framework , Microsoft directs users to the dedicated forums . Feedback on the SDK is also encouraged in the AG-UI repository, where the community can contribute to refining features.
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