CS File

What are CS files and how to open them

Are you having problems opening a CS file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CS files.

What is a CS file?

CS files have multiple uses, and C# Source Code is one of them. Read more about the other uses further down the page.

C# Source Code File

Files that contain the .cs file extension are files that contain source code written in the C# ("C-Sharp") programming language. C# is a programming language used to create a variety of .NET applications. It is commonly created with the Microsoft Visual C# toolset.

The CS files are usually compiled by a csc.exe file. The types of source code code that a CS file can contain may include source code for console applications, library files and GUI applications.

How to open CS files

We have identified five CS openers that are compatible with this specific type of CS file.

Programs that open C# Source Code files

Last updated: September 19, 2026

All known file formats using extension .CS

While C# Source Code File is a popular type of CS-file, we know of 2 different uses of the .CS file extension. Different software may use files with the same extension for different types of data.

ColorSchemer Studio Color Scheme

ColorSchemer Studio Color Scheme files hold custom color palettes created with the ColorSchemer Studio application for design purposes. These files store a set of colors (often arranged in a scheme or swatch) that a user has crafted or saved during work inside ColorSchemer Studio.

Such files are produced by saving a color scheme from ColorSchemer Studio. Designers may later reopen the saved scheme within that same application to view or modify the palette. Schemes stored this way can also be exported to other color interchange formats for use in web design, graphics programs, or print layouts.

Internally the file is a binary format: files are little-endian, begin with a signature that includes the ASCII letters "CS", followed by metadata such as a version number (int16), the number of colors (int16), a base RGB color (3 bytes), and then a list of color entries. Each color entry has RGB values (3 bytes), a name (length-specified string), and additional attributes such as whether the color is "developed" (enabled) inside the color list.

Byte signatures include the bytes 0x43 0x53 0x01 0x00 0x00 0x00 0x01 0x00 at offset zero.

While we have not verified the apps ourselves yet, our users have suggested ten different CS openers which you will find listed below.

Various apps that use files with this extension

These apps are known to open certain types of CS files. Remember, different programs may use CS files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

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