What is SimpleW?

SimpleW is a .NET Core library designed for building fast and secure web applications.

Just want to try it out? Skip to the Quickstart.

Architecture

SimpleW’s architecture and motivations behind its core design choices :

• Pure C# (100% managed code), running on .NET 8 or later.
• Built on top of native sockets, no HttpListener inside.
• Compiled delegate, close to hard-coded method calls.
• Event model, low latency and low memory.
• Cross‑platform support, Windows/Linux/Android/macOS.
• Single dependency: Newtonsoft.Json for serialization/deserialization
• NuGet package available, easy to integrate

It is based in the great NetCoreServer socket server.

Use Cases

• High‑Performance

When network efficiency and observability are critical, SimpleW ensures fast request throughput and low latency. Coupled with automatic OpenTelemetry instrumentation, you gain full visibility into request flows, latency, and error rates—enabling you to scale horizontally with confidence.

• Rapid API Prototype

When you need to deliver a proof‑of‑concept API in record time, SimpleW excels. Its minimal configuration lets you define endpoints in just a few lines of code. With JSON serialization handled automatically and no heavyweight server plumbing to configure, developers can focus on business logic from the very first compile.

• Embedded Service

When resources are constrained, SimpleW’s tiny memory footprint and makes it ideal for lightweight background services, command‑and‑control agents, or any situation where simplicity and reliability are paramount.

• static site

Need to ship a single‑page app or docs alongside your API? With SimpleW you point to a folder (e.g. wwwroot), mount it under a URL, and in milliseconds all your files are served with caching—no heavy framework required. Fast, lean, and ready for your Vue.js dashboard or static site...

Why this library ?

I believe modern web application architecture should be based on a REST API which acts as a contract between 2 parts :

• backend (only one) : developer feels free to use/change the technology he wants (C#, Go, Rust, PHP...) but must provide and follow the REST API.
• frontend (one or many) : developer feels free to use/change the technology he wants (SPA/Vue, SPA/React, Mobile/Android...) but must consume and follow the REST API.

My needs

Frontend :

• I prefer SPA using Vite, Vue and Vuetify.

Backend :

• written in C#, the language i 😍.
• must be easy to integrate, lightweight with a minimal footprint.
• must support Routing, Websocket, SSE, CORS.
• don't need to have template engine as i write frontend in a separated project.
• must serve static files (static files are the result of my npm run build vite project)
• observality : trace each request and monitor performances

The existings projects

• ASP.NET Core :
  • too many features i don't need, i don't want (Razor, Blazor...).
  • overcomplicated to customize some behaviour
  • too heavy, sometimes i have a very small API.
• IIS an old « usine à gaz » on Windows, Kestrel and SignalR the same on Linux.
• EmbedIO : long time v2 user, i dislike the rewrite of the v3. Moreover, it uses the old Microsoft HttpListener and the websocket-sharp alternative was not perfect.
• GenHttp : feels promising but i was in the process of writting my own.
• NetCoreServer : WHOA 😮 ! Fast, simple, extremly well design, extendable BUT no RESTAPI... Wait, what if i use the whole OnReceivedRequest() event to do exactly what i want 🤔

This project

SimpleW is the result of adding features to the OnReceivedRequest() of NetCoreServer.

After 3 years grade production, SimpleW serves many APIs without any issue, gains some cool features but still always lightweight and easy to integrate.

Feel free to report issue.