CSPROJ is a developer file format used by Microsoft Visual Studio development environment. CSPROJ file contains a C Sharp project in MSBuild format. The file stores information regarding resources needed by given program and setting used during compilation.

CSPROJ documents are written in C#, a programming language developed by Microsoft inner team lead by Andersa Hejlsberga between 1998 and 2001, and later upgraded. Latest version of C# is designated C# 5.0.