Write, compile, and run C# in your browser with a real .NET toolchain behind it. The Monaco
editor gives you C# syntax highlighting, find-and-replace, and formatting; the file explorer
lets you build small multi-file projects; and the standard-input panel feeds
Console.ReadLine() so interactive programs work too. Pick a starter template or paste your
own code and see actual compiler output — including real diagnostics when something doesn't build.
Best Fit
- Try a C# language feature or a quick algorithm without opening an IDE.
- Reproduce a small bug across two or three files and share the exact repro.
- Run a console program that reads input, then read its output inline.
How to use C# Compiler
- Start from an example (Hello World, FizzBuzz, Fibonacci, Bubble Sort, and more) or write your own.
- Add files with the explorer if your program spans more than one class.
- If your code calls
Console.ReadLine(), open the Input panel and add one line per read. - Press Run (or Ctrl+Enter) to compile and execute; read output and any diagnostics below.
- Copy the code, or download the file — multi-file projects download as a zip.
What C# Compiler helps with
- Real .NET compilation that surfaces genuine build errors and warnings, not just red squiggles.
- Multi-file projects with a file explorer, tabs, and search across files.
- Standard-input support so interactive
Console.ReadLine()programs run as intended. - Quality-of-life editing: format, minify, find and replace, word wrap, and a minimap toggle.
Examples
Hello World
Input
Console.WriteLine("Hello, World!");
Output
Hello, World!
Reading input with stdin
Input
var name = Console.ReadLine();
Console.WriteLine($"Hi {name}, your name has {name?.Length} letters.");
Input panel:
Ada
Output
Hi Ada, your name has 3 letters.
Frequently Asked Questions
Where does my code run?
Your code is sent to the Parsepad backend, compiled with a real .NET toolchain, and executed in a sandbox; the output is returned to your browser. Unlike a purely client-side tool, running requires a network round-trip — which is what lets it report genuine compiler diagnostics.
Can I run programs that read input?
Yes. Open the Input panel from the status bar and enter one line for each Console.ReadLine()
call your program makes. The lines are fed to standard input in order when you run.
Does it support multiple files?
Yes. Use the file explorer to add classes across several .cs files. When you download a
multi-file project it is packaged as a zip so the structure is preserved.
Which C# and .NET version is used?
A current .NET runtime. Language features available in the latest stable C# generally work; platform-specific or long-running operations are limited by the execution sandbox.
