OllyDbg
What it is
OllyDbg is a free 32-bit assembler-level debugger for Microsoft Windows, intended for binary analysis when source code is unavailable. It traces registers and recognizes procedures, loops, API calls, switches, tables, constants, and strings. The debugger can load DLLs, attach to running programs, and handle multithreaded applications. Breakpoint choices include conditional, logging, memory, and hardware types, and execution tracing can log arguments for known functions. Patches may be saved between sessions, written back to executable files, and used to update fixups. An open architecture supports third-party plugins, with a Plugin Development Kit and documented samples from the maker. Requirements list Windows 95, 98, NT 4.0, 2000, or higher; Win32s is unsupported. Development is frozen and the 64-bit version is incomplete. Registration is free and requested for permanent or commercial use.
For and against
For
- Analyzes binary code without source
- Supports conditional and hardware breakpoints
- Can debug DLLs and multithreaded programs
- Saves and writes executable patches
- Open architecture supports third-party plugins
Against
- Development is frozen
- 64-bit version is incomplete
- Cannot analyze only a selected code section
- Registration requested for permanent or commercial use
The verdict
OllyDbg provides extensive 32-bit debugging and patching functions at no cost. Its frozen development and incomplete 64-bit version define the main limits for current use.
Who it suits
OllyDbg suits Windows users analyzing 32-bit binary code without source access. It also fits users who need breakpoints, patching, tracing, or plugin support.
Plans and prices
OllyDbg
Free to download and use · Registration is free and requested for permanent or commercial use
Read 8 Oct 2026 · ollydbg.org
On the record
- Analysis limit
- The FAQ says OllyDbg cannot analyze only a selected piece of code because changes can affect analysis outside that selection.ollydbg.org · read 8 Oct 2026
- Breakpoints and tracing
- It supports conditional, logging, memory, and hardware breakpoints, and can trace execution while logging arguments of known functions.ollydbg.org · read 8 Oct 2026
- Code analysis
- It traces registers and recognizes procedures, loops, API calls, switches, tables, constants, and strings.ollydbg.org · read 8 Oct 2026
- Compatibility
- The maker lists Microsoft Windows 95, 98, NT 4.0, 2000, or higher as system requirements; OllyDbg does not work under Win32s.ollydbg.org · read 8 Oct 2026
- Debugging
- It can load and debug DLLs, attach to running programs, and debug multithreaded applications.ollydbg.org · read 8 Oct 2026
- Development status
- The maker says development is frozen and describes the 64-bit version as incomplete.ollydbg.org · read 8 Oct 2026
- Patching
- It saves patches between sessions, writes them back to executable files, and updates fixups.ollydbg.org · read 8 Oct 2026
- Plugins
- Its open architecture supports third-party plugins, and the maker provides a Plugin Development Kit with documented sample plugins.ollydbg.org · read 8 Oct 2026
- Privacy
- For original versions 1.00–1.10, the maker says OllyDbg does not act as a network client or server or send data to another computer, except for remote files specified by the user.ollydbg.org · read 8 Oct 2026
- Purpose
- OllyDbg is a 32-bit assembler-level debugger for Microsoft Windows, intended for binary code analysis when source code is unavailable.ollydbg.org · read 8 Oct 2026
- Registration
- The maker says registration is free, carries no financial or other obligations, and is requested for permanent or commercial use.ollydbg.org · read 8 Oct 2026
- Security caveat
- The maker warns that it cannot guarantee archives or third-party modifications are free from viruses or Trojan horses.ollydbg.org · read 8 Oct 2026
- Support
- The FAQ says the author usually answers email questions within 1–3 days.ollydbg.org · read 8 Oct 2026
