yarp

YARP (Yet Another Reverse Proxy) is Microsoft's toolkit for building custom proxy servers in C#. Instead of configuring Nginx or Envoy, you write your proxy logic in .NET: routing rules, load balancing, request transforms, health checks, all in C# code or configuration.

The key difference from traditional proxies: YARP is a library, not a standalone server. You embed it in your ASP.NET application, which means your proxy logic lives alongside your business logic. Custom routing based on database lookups, dynamic configuration changes, request manipulation, all in the language your team already knows. MIT, backed by Microsoft, used internally. Fully free.

The catch: this only makes sense if your team is already .NET. If you're not in the Microsoft ecosystem, Nginx, Caddy, Traefik, or Envoy are all better choices. YARP's sweet spot is teams that need custom proxy behavior and want to write it in C# rather than learning Envoy's filter chain or Nginx's Lua scripting.