Introduction to Kestrun (PowerShell)

Kestrun is a lightweight, cross‑platform web server you can configure entirely from PowerShell (and optionally mix with C# or VB.NET inline). It sits on ASP.NET Core Kestrel, so you get performance, HTTP/1.1–HTTP/3 support, TLS, compression, and familiar middleware patterns — with simple PowerShell cmdlets.

This chapter gives you a hands‑on start using three tiny samples you can run immediately:

  • Sample-1: Hello World route returning plain text
  • Sample-2: Multiple content types (text, JSON, XML, YAML)
  • Sample-3: Multi-language routes (PowerShell, C#, VB.NET)

Routing styles (two ways to define endpoints)

Kestrun supports two common routing styles in PowerShell:

  • Imperative routing (explicit mapping): you call Add-KrMapRoute and provide a script block.
  • Declarative attribute routing (function + attributes): you decorate a function with [OpenApiPath(...)] (and optionally other OpenAPI attributes).

If you want a side-by-side comparison (including what “runtime status codes” vs “OpenAPI documented responses” means), see:

All sample scripts live in examples/PowerShell/Tutorial.

Next steps

  • Dive into the other Tutorial chapters (Certificates, Logging, Razor Pages, Scheduling)
  • Explore the richer example scripts under examples/PowerShell (e.g., MultiRoutes.ps1)
  • Browse the PowerShell cmdlet reference under docs/pwsh/cmdlets
  • Explore the PowerShell module source at src/PowerShell/Kestrun

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