OllyDbg

Free plan Windows

What OllyDbg is

OllyDbg is a free 32-bit assembler-level debugger for Microsoft Windows, designed to analyze binary code when source code is unavailable. It traces registers and identifies procedures, loops, API calls, switches, tables, constants, and strings. You can load and debug DLLs, attach to running programs, and work with multithreaded applications. Breakpoint options include conditional, logging, memory, and hardware types; execution tracing can log arguments for known functions.

OllyDbg can save patches between sessions, write them back to executable files, and update fixups. Its open architecture supports third-party plugins, and the maker provides a Plugin Development Kit with documented sample plugins. The maker lists Windows 95, 98, NT 4.0, 2000, or higher as system requirements, and says OllyDbg does not work under Win32s. Development is frozen, and the 64-bit version is incomplete. The software is free to download and use; free registration is requested for permanent or commercial use.

Who it suits

OllyDbg suits Windows users who need to examine binary code without source code, including work involving DLLs, running programs, or multithreaded applications. Its plugin architecture and development kit may also suit users who want to extend the debugger.

What it does well

Free to download and use, with free registration.
Analyzes registers and recognizes common code structures and data.
Can debug DLLs and attach to running programs.
Supports conditional, logging, memory, and hardware breakpoints.
Can save patches and write them back to executable files.
Supports third-party plugins and provides a plugin development kit.

What to know first

Development is frozen.
The 64-bit version is incomplete.
Does not work under Win32s.
Registration is requested for permanent or commercial use.

Limits

The maker describes development as frozen and the 64-bit version as incomplete. Registration is requested for permanent or commercial use.

Plans

Plan	Billed and limits	Price
OllyDbg	Free to download and use · Registration is free and requested for permanent or commercial use	Free

As ollydbg.org lists them, read 8 Oct 2026. The maker's own page has the final word.

Getting started

Visit the OllyDbg website.
Download and use the free software on a supported Microsoft Windows system.
Register for free if using it permanently or commercially.

Verdict

Choose OllyDbg if you need a free Windows debugger for binary analysis and value its breakpoint, tracing, patching, and plugin options. Look elsewhere if you need ongoing development or a complete 64-bit version.

Questions

How much does OllyDbg cost?

The listed plan is free. It is free to download and use.

Is there a free plan or trial?

There is a free plan. No free trial is offered.

Which platforms does it support?

OllyDbg supports Microsoft Windows. The maker lists Windows 95, 98, NT 4.0, 2000, or higher as system requirements and says it does not work under Win32s.

Is OllyDbg open source?

The listed facts describe an open architecture for third-party plugins, not open-source software.

Does it support plugins?

Yes. Its open architecture supports third-party plugins, and the maker provides a Plugin Development Kit with documented sample plugins.

Is development ongoing?

No. The maker says development is frozen and describes the 64-bit version as incomplete.

Facts from OllyDbg's own pages

Analysis limit: The FAQ says OllyDbg cannot analyze only a selected piece of code because changes can affect analysis outside that selection. · ollydbg.org, 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, 8 Oct 2026
Code analysis: It traces registers and recognizes procedures, loops, API calls, switches, tables, constants, and strings. · ollydbg.org, 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, 8 Oct 2026
Debugging: It can load and debug DLLs, attach to running programs, and debug multithreaded applications. · ollydbg.org, 8 Oct 2026
Development status: The maker says development is frozen and describes the 64-bit version as incomplete. · ollydbg.org, 8 Oct 2026
Patching: It saves patches between sessions, writes them back to executable files, and updates fixups. · ollydbg.org, 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, 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, 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, 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, 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, 8 Oct 2026
Support: The FAQ says the author usually answers email questions within 1–3 days. · ollydbg.org, 8 Oct 2026

Where OllyDbg stands on Freedom251

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