Semantic Kernel (.NET)

Microsoft’s enterprise SDK for .NET. Semantic Kernel for C# brings plugins, planners, vector stores, MCP, and A2A into your ASP.NET Core, Azure Functions, and desktop apps with full Polly resilience and Application Insights observability.

Install

dotnet add package Microsoft.SemanticKernel

Version

v1.74.0 · April 2026 · .NET 6.0+

Best for

Azure-native .NET apps, enterprise plugins, ASP.NET integrations.

Agent Framework or Semantic Kernel?

Microsoft Agent Framework unifies SK + AutoGen. For new projects, consider Agent Framework (.NET). Semantic Kernel has the richer plugin/planner ecosystem today.

Zero → Hero

1 · Installation & setup NuGet, builder, auth · 15 min

2 · Kernel initialization Builder, services · 15 min

3 · Service configuration Azure OpenAI, HuggingFace · 15 min

4 · Functions & plugins Semantic + native functions · 25 min

5 · Agents & multi-agent ChatCompletionAgent, group chat · 25 min

6 · Memory & vector stores v1.34 New vector store API · 20 min

7 · Planners Sequential, Stepwise · 20 min

8 · MCP (March 2025) MCP client + server · 20 min

9 · Google A2A protocol Cross-framework interop · 20 min

10 · Agent Framework bridge SK ↔ Agent Framework · 15 min

11 · Structured output Validated JSON output · 15 min

12 · Error handling (Polly) Retry, circuit breaker · 15 min

13 · Observability (App Insights) Distributed tracing · 15 min

14 · ASP.NET Core integration DI, hosting, controllers · 20 min

15 · Best practices Security, cost, patterns · 15 min

16 · Production Deployment, scaling · 30 min

Jump to a topic

Kernel initialization

Functions & plugins

Agents & multi-agent

Vector stores v1.34

Planners

MCP

A2A protocol

Agent Framework bridge

Polly resilience

ASP.NET Core

Reference

Comprehensive (.NET) Single-page technical reference.

Recipes

Diagrams

Production guide

What’s new in v1.74.0 (April 2026)

• Vector stores v1.34 — new abstractions with pluggable providers.
• MCP client + server (March 2025).
• Google A2A protocol integration.
• Microsoft Agent Framework bridge for gradual migration.
• Polly v8 resilience patterns.

Install, minimal example

using Microsoft.SemanticKernel;
using Microsoft.SemanticKernel.ChatCompletion;

var builder = Kernel.CreateBuilder();
builder.AddOpenAIChatCompletion("gpt-4o", Environment.GetEnvironmentVariable("OPENAI_API_KEY")!);
var kernel = builder.Build();

var chat = kernel.GetRequiredService<IChatCompletionService>();
var history = new ChatHistory("You are a helpful assistant.");
history.AddUserMessage("What is 15 + 27?");

var result = await chat.GetChatMessageContentAsync(history, kernel: kernel);
Console.WriteLine(result.Content);

Ready? Start Zero → Hero Step 1 →

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Revision history

Date	Version	Changes
2026-04-21	1.74.0	Index redesigned with Zero → Hero + Jump-to-topic grid.
April 2026	1.74.0	Vector stores v1.34; MCP; A2A; Agent Framework bridge.

Other languages: Python.