Data file
What is a .dll file?
A .dll is a Dynamic Link Library — shared code that Windows programs load while they run. It's a system file, not a document, and you're not meant to open it. If you landed here because of a "missing DLL" error, the fix is almost never to download the DLL.
Avoid "DLL download" websites — they're a classic malware vector. Get DLLs only from the software vendor or from Windows itself.
This extension has been used by more than one format
3 different formats have claimed .dll over the years, so two files with the same extension aren't necessarily the same kind of thing.
How to open a .dll file
- WindowsNothing, normally
- WindowsDependency Walker or dotPeek, if you're a developer inspecting it
How to convert a .dll file
- DLLs can't be converted. To fix a missing-DLL error, reinstall the program that needs it, or install the Microsoft Visual C++ Redistributable.
MIME type
When a .dll file travels over the web, servers label it with this MIME type:
application/vnd.microsoft.portable-executableThe technical record
For archivists, developers and the merely curious: these are the PRONOM registry entries for .dll.
| Format name | Version | MIME type | PUID |
|---|---|---|---|
| Windows Portable Executable | — | application/vnd.microsoft.portable-executable | x-fmt/411 |
| Windows Portable Executable | 32 bit | application/vnd.microsoft.portable-executable | fmt/899 |
| Windows Portable Executable | 64 bit | application/vnd.microsoft.portable-executable | fmt/900 |