PE Explorer is the most feature-packed tool for inspecting the inner workings of PE files (EXE, DLL, ActiveX controls, and several other Windows executable formats). It comes with a PE File Viewer, Disassembler, Exported/Imported API Function Viewer, API Function Syntax Lookup, Resource Editor & Dependency Scanner. Once inside, file structure can be analyzed and optimized, problems diagnosed, changes made and resources repaired. It tells you just about every little detail you could possibly want to know about a PE file. On top of all that, this program has one of the best UPX Unpackers built in.