.dylib

What is a .dylib file?

Dylib is macOS's shared library format — the Mac equivalent of Windows DLL and Linux SO.

Use caution
Type System
By Apple Inc.
MIME application/x-mach-binary

Drop any file to identify it

No upload. No signup. No sending your file halfway across the internet.
We tell you what it is, right here in your browser.

What is it

Dylibs are macOS's mechanism for shared libraries — compiled code loaded by applications at runtime. Every Mac app uses them: system frameworks, third-party libraries, and even parts of the operating system are dylib files. They live in `/usr/lib/`, framework bundles, and application packages.

Apple's dynamic linker (`dyld`) handles loading dylibs at application launch. The `otool -L` command shows which dylibs an application depends on. `install_name_tool` modifies library paths embedded in binaries — essential when distributing applications that bundle their own libraries.

With macOS's transition to Apple Silicon, dylibs may contain universal binaries (both x86_64 and arm64 code) or single-architecture slices. System Integrity Protection (SIP) prevents modification of system dylibs, and recent macOS versions require dylibs to be code-signed or notarized.

Technical details
Full Name
macOS Dynamic Library
MIME Type
application/x-mach-binary
Developer
Apple Inc.
Magic Bytes
CF FA ED FE
Safety
.dylib requires caution. Compiled binary code. System dylibs are protected by SIP. Only install dylibs from trusted sources.
What opens it
otool (CLI)
FREE Mac
Hopper Disassembler
$99 Mac / Linux
Ghidra
FREE Windows / Mac / Linux
FAQ
What's the difference between .dylib and .framework?
A .framework is a bundle (directory) containing a dylib plus headers, resources, and metadata. A .dylib is just the library binary. Frameworks are Apple's preferred packaging for Mac/iOS libraries.
Can I delete dylib files?
Never delete system dylibs — SIP protects them for a reason. For application-bundled dylibs, removing them will break that application. Use the standard uninstaller instead.
Related formats