otool

OTool, commonly written otool, is a macOS command-line utility used to analyze Mach-O binary files, object files, and libraries. It is included with Xcode and the macOS Command Line Tools and is used by developers and reverse engineers to inspect binary structure and linking information.

OTool can display details such as the Mach-O header, load commands that describe segments and dynamic linker information, and the symbol table or exported symbols. It reveals which dynamic libraries a binary depends on and how it is linked against system frameworks. For binaries containing multiple architectures, otool can report per-architecture information and allows selecting a target architecture with the appropriate option.

Typical uses include confirming library dependencies, auditing for compatibility with specific macOS versions, and inspecting sections or segments of code. The tool is primarily macOS-specific and is not natively available on Linux or other platforms; similar functionality on other systems is provided by tools such as readelf or objdump.

OTool complements other development and debugging utilities, such as nm for symbol listing and codesign for code signing related details. It is commonly employed in development workflows, build verification, and security research to quickly understand how a binary is composed and how it interacts with the system’s dynamic linker.