OllyDbg

OllyDbg is an x86 debugger that emphasizes binary code analysis, which is useful when source code is not available. It traces registers, recognizes procedures, API calls, switches, tables, constants and strings, as well as locates routines from object files and libraries. Version 1.10 is the final 1.x release. Version 2.0 has recently been released, and OllyDbg has been rewritten from the ground up in this release. The software is free of cost, but the shareware license requires users to register with the author. The current version of OllyDbg cannot always disassemble binaries compiled for 64-bit processors, though a 64-bit version of the debugger has been promised.

OllyDbg is often used for reverse engineering of programs. It is often used by crackers to crack software made by other developers. For cracking and reverse engineering, it is often the primary tool because of its ease of use and availability. It is also useful for programmers to ensure that their program is running as intended.