This a .bundle file compiler.

Compiles Web Essentials .bundle files in command line, useful as build step for continuous integration. This also means that only bundle files and source files need to commited to source control.

Command Prompt / Powershell example.

BundleCompiler.exe js/bundle.js.bundle

The above code would generate bundle.js, bundle.min.js and bundle.min.js.map in the same directory as bundle.js.bundle