How to open a .dll file
Dynamic Link Library · Executable / library
A .dll file is compiled code that programs load, not something you open. If a program says a DLL is missing, install the runtime it belongs to. Never download an individual DLL from a website.
What a .dll file actually is
A DLL holds functions that several programs share, so the code exists once on disk instead of inside every application. Windows itself is built almost entirely out of them.
It is compiled machine code in the same Portable Executable format as an .exe, with the difference that it cannot start on its own. Something else has to load it.
Why it will not open
There is nothing to open, and that is the honest answer. People arrive here for one of two reasons: a program reported a missing DLL, or they want to inspect what is inside one.
Step by step
Windows
- 01If a program reports a missing DLL, identify the runtime it belongs to rather than hunting for the file. VCRUNTIME140 and MSVCP140 come from the Visual C++ Redistributable; d3dx9 files come from the DirectX End-User Runtime; MSVCR100 comes from the 2010 redistributable.
- 02Install that official runtime. The DLL arrives with it, in the right place, correctly registered.
- 03To inspect a DLL, open it in a resource viewer or a disassembler. To see just its icons and strings, a resource editor is enough.
- 04To see raw bytes, HxD opens it as a hex dump.
macOS
- 01DLLs are Windows-specific. macOS uses .dylib for the same job.
- 02A Windows DLL cannot be loaded on macOS other than inside Wine or a virtual machine.
What usually goes wrong
DLL download sites are a malware channel
Searching for a missing DLL by name leads straight to sites offering that single file. This is one of the oldest and most effective malware delivery methods there is. There is no legitimate reason to obtain a system DLL that way: install the runtime package it belongs to instead.
Registering a DLL rarely fixes anything
Advice to run regsvr32 is copied endlessly and applies only to COM components. For a missing runtime DLL it does nothing, because the problem is that the file is not there, not that it is unregistered.
Programs that open .dll
Our pick, in order. Every one links to the publisher's official download URL and the SHA-256 hash of the installer, so you can check the file before you run it.
Common questions
- A program says a .dll is missing. What do I do?
- Install the runtime package that DLL belongs to, not the file itself. VCRUNTIME140 and MSVCP140 come from the Visual C++ Redistributable, d3dx9 files from the DirectX End-User Runtime. Downloading a lone DLL from a website is a well-known malware vector.
- Can I open a DLL to see what is inside?
- You can inspect one with a resource viewer or disassembler, and view its raw bytes in a hex editor such as HxD. You cannot run it directly, because a DLL has no entry point of its own.