Scalar API documentation UI for .NET 10 applications. Covers setup, themes, authentication prefill, multiple documents, layout options, and security. A modern replacement for Swagger UI. Load this skill when setting up API documentation UI, or when the user mentions "Scalar", "MapScalarApiReference"

Scalar Core Principles 1. Scalar replaces Swagger UI — Scalar is the recommended API documentation UI for .NET 10. Faster rendering, built in dark mode, code generation for dozens of languages, and full OpenAPI 3.1 support. 2. Development only by default — Wrap MapScalarApiReference() in an IsDevelopment() check. API documentation exposes internal structure. If needed in production, add authorization. 3. Disable the proxy for sensitive APIs — Scalar's "Try It" feature routes through proxy.scalar.com by default. Disable it with .WithProxy(null) to keep auth headers local. 4. Security schemes come from OpenAPI — Scalar reads security schemes from the OpenAPI document. Configure them via document transformers, not in Scalar directly. Patterns Basic Setup Customized Configuration Authentication Prefill (Development Only) Pre fill credentials so developers don't have to paste tokens manually. The OpenAPI document must already include the security scheme via a document transformer. Other auth types: Available Themes Multiple API Documents Or configure documents explicitly: Custom Route Prefix Production with Authorization Force Dark Mode Classic Layout (Swagger like) Anti patterns Don't Expose Scalar in Production Without Auth Don't Pre fill Real Credentials Don't Forget the Security Scheme Transformer Don't Leave the Proxy Enabled for Sensitive APIs Don't Use Swagger UI for New .NET 10 Projects Decision Guide Scenario Recommendation API documentation UI MapScalarApiReference() with MapOpenApi() Development environment Default setup with IsDevelopment() guard Production API docs Add .RequireAuthorization() to both endpoints Auth testing in dev AddHttpAuthentication() with test tokens Dark theme preference .ForceDarkMode() or .WithTheme(ScalarTheme.Moon) Multiple API versions Multiple AddOpenApi() calls — Scalar detects automatically Sensitive APIs .WithProxy(null) to disable external proxy Swagger like layout .WithClassicLayout() Custom route app.MapScalarApiReference("/api docs")