API Key Authentication and Scalar Implementation in .NET 9 and more

This project demonstrates how to implement API Key authentication, modify endpoint metadata, utilize Scalar in .NET 9, and versioning. Hope you find this useful.

Technologies Used

.NET 9

Visual Studio 2022 (version 17.12.0)

Scalar.AspNetCore 1.2.39

APIWeaver.OpenApi

Features

• API Key authentication
• Endpoint metadata modification
• API versioning
• Scalar implementation

Requirements

• .NET 9 SDK

• Visual Studio 2022

API Versions Documentation

• /scalar/v1
• /scalar/v2

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New: .NET 10 Implementation

A .NET 10 implementation has been added alongside the existing .NET 9 project. The .NET 9 implementation above is left unchanged. The .NET 10 project lives in the scalar.net10.api folder and demonstrates the same patterns (API Key authentication, OpenAPI metadata modification, Scalar UI) updated for .NET 10.

Technologies Used (for .NET 10)

• .NET 10
• Visual Studio 2026
• Scalar.AspNetCore (used in scalar.net10.api)

Features

• API Key authentication (same approach as .NET 9, updated for the .NET 10 project)
• Endpoint metadata modification for OpenAPI
• API versioning with versioned endpoints
• Scalar UI integration and configuration

Requirements (for .NET 10)

• .NET 10 SDK
• Visual Studio 2026 (or use the SDK with CLI)

Quick start for the .NET 10 project

• Build:
  • dotnet build ./scalar.net10.api
• Run:
  • dotnet run --project ./scalar.net10.api
• Or open the solution/project in Visual Studio 2026 and run/debug from the IDE.

Notes

• Both implementations expose API documentation for the same versioned endpoints (for example /scalar/#api-v1 and /scalar/#api-v2). The .NET 10 project follows the same routing/versioning conventions and adds any project-level updates required for .NET 10 and C# 13.