# OllyDbg

> 32-bit assembler-level analyzing debugger for Windows that emphasizes binary code analysis for programs without source; its site says development is frozen, and the newest version it lists is 2.01 of 27 September 2013. Its analysis recognizes procedures, loops, API calls, switches, tables, constants and strings and decodes calls to more than 1,900 standard API and 400 C functions; it attaches to running programs, debugs DLLs directly, sets conditional, logging, memory and hardware breakpoints and writes patches back to the executable.

- Type: Tool
- Targets: Binary
- Category: Debugging and dynamic analysis
- Relationship: Foundation tool
- Sources reviewed: 2026-11-05
- Added to the catalog: 2026-11-06
- Original resource: <https://www.ollydbg.de/>
- Primary source: <https://www.ollydbg.de/viewer.htm>
- Catalog page: <https://awesomerea.org/resources/ollydbg/>
- Record JSON: <https://awesomerea.org/resources/ollydbg/record.json>
- Chinese version: [简体中文](https://awesomerea.org/zh/resources/ollydbg/index.md)

## Requirements & limits

- **Prerequisites:** Version 2.01 (27 September 2013) is the newest the site lists, and 1.10 is offered as the final 1.x version. The requirements page lists Windows 95, 98, NT 4.0 SP2 or later, or Windows 2000 and later, and says debugging on NT or 2000 may need administrative rights; the 2.x notes say version 2 does not run on Windows 95 or 98.
- **Limits:** OllyDbg is a 32-bit debugger. The 64-bit version is offered only as incomplete, and its latest progress note, of 5 February 2014, put the debugging engine at 70% and analysis at 15%.
- **License:** Shareware that may be downloaded and used for free; the FAQ says it is rated shareware for copyright reasons only. The download page's agreement covers only version 1.10 and its Plugin Development Kit: permanent or commercial use needs a free registration, the software comes as is, and copies may be shared only complete, unchanged and without a fee. Disassembler 2.01 is released under GPL v3.
- **Limits:** The download page warns that many vendors forbid disassembling, decompiling or reverse engineering their programs, including third-party and system libraries, and suggests asking a lawyer whether fair use applies.

## Primary sources

1. <https://www.ollydbg.de/viewer.htm>
2. <https://www.ollydbg.de/version2.html>
3. <https://www.ollydbg.de/download.htm>
4. <https://www.ollydbg.de/requires.htm>
5. <https://www.ollydbg.de/odbg64.html>
6. <https://www.ollydbg.de/faq.htm>

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## About this entry

The description was reviewed against primary sources.
Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.