CFR vs ILSpy

CFR is a free Java decompiler that reconstructs Java source from Java class files. It can process individual named classes, classes found on a classpath, or a whole JAR, and the command-line tool can place output in a chosen directory with the --outputdir option. Decompilation behavior can be adjusted through command-line options or an options file. The maker says CFR handles many features from Java 9, 12, and 14, and it can attempt class files from other JVM languages; those are rendered as Java rather than their original language. CFR is written in Java 6 and is said to run wherever Java 6 does. It is available as a downloadable JAR, through Maven, and from GitHub. The FAQ notes an API from version 0.135, and the project repository identifies the license as MIT. CFR handles bytecode rather than native code. Its maker also notes that some inputs fall into edge cases where output may be poor. There are no paid plans or usage limits stated.

ILSpy is free, open-source software for browsing and decompiling .NET assemblies on Windows, Linux, and macOS. Its Avalonia desktop interface converts assemblies to C#, including whole-project decompilation. Assemblies can come from disk, NuGet, running processes, or the Global Assembly Cache, although GAC support is limited to Windows. Search covers types, methods, and properties, with hyperlinks, bookmarks, base and derived type navigation, and an assembly metadata explorer. The application also includes BAML-to-XAML decompilation and support for ReadyToRun binaries for .NET Core. Related tooling includes Visual Studio 2022/2026 support, Visual Studio Code extensions, the ilspycmd dotnet tool, PowerShell cmdlets, and NuGet packages. Desktop plugins and a scripting API extend its use. ILSpy supports bytecode decompilation but not native-code decompilation. The project says it does not collect personally identifiable information, send user files to third-party services, or use application performance monitoring for telemetry. Release 11.1 is listed as the latest version, under the MIT License.