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Latest version for Visual C++ is 1.1.2, released on 2008-07-30 (see changes).
Latest version for other compilers is 1.1.1, released on 2005-01-06.

What is libunicows?

Traditionally, win32 Unicode API was only available on Windows NT or 2000. If you wanted to take advantage of Unicode in your application and support Windows 95/98 at the same time, your only option was to deploy two executables, one for NT and one for 9X. Fortunately, this changed in 2001 when MS (finally!) released MSLU runtime that allows Unicode applications to run under Windows 9X.

See these pages for details:

Less fortunately, this solution requires that you use a special statically linked import library that decides at runtime whether to load symbols from system libraries like kernel32.dll or user32.dll (in case of Windows NT) or from unicows.dll (which provides Unicode emulation layer under 9X). This import library is only available for Microsoft Visual C++ and is only part of the new Platform SDK, which is rather huge package.

libunicows contains independent implementation of the import library. It can be used with any C compiler (although it was only tested with Mingw32, MSVC and Borland compilers so far) and is released under the Open Source MIT license (this permits you to link the library into your executable without any restrictions).

For compilers where "native" import library is not available in precompiled form or is impossible/difficult to create (this is the case of e.g. Borland C++ which doesn't use COFF libraries), libunicows provides alternative mean of using unicows.dll (beginning with version 0.6). There is a version of unicows import library compiled as a DLL, called unicows_wrapper.dll. You can create import library for the wrapper as you do with any other DLL and calls to Unicode API functions will go through the wrapper DLL. Unlike when creating such import library for unicows.dll, unicows.dll is not used on NT/2000/XP systems when using the wrapper.

Alternatives to MSLU

MSLU comes with licensing terms that are highly unfriendly to Open Source applications: although you can freely distribute unicows.dll with your application, your licensing terms must meet certain conditions that no Open Source license can. Namely, you must forbid further redistribution and the license must be an EULA accepted by the user either in writing or using click-through or shrink-wrap mechanism.

To overcome this obstancle, the Mozilla project began reimplementing similar solution under Open Source terms: Opencow: Open Layer for Unicode (see also discussion in bugzilla). Althought it's nowhere need MSLU's API coverage yet, it already implements some functions that MSLU doesn't.

Latest version of libunicows supports both unicows.dll and opencow.dll.


Microsoft Visual C++ 6
Borland C++
Watcom C/C++
Source code libunicows-1.1.2-src.tar.gz

See also the project page


version 1.1.2 version 1.1.1 version 1.1.0 version 1.0.0 version 0.7.0 version 0.6.5 version 0.6.4
version 0.6.3
version 0.6.2:
version 0.6.1:
version 0.6:
version 0.5:
initial release


Important note: I wrote libunicows import library, not MSLU/unicows.dll itself. If you have problems with making MSLU work or if you have problems with some software using unicows.dll, don't write to me! I can't and won't do anything about it. On the other hand, feedback from developers about the import library from this site is most welcome and so are bug reports for bugs in the import library itself (e.g. when MSLU doesn't work because libunicows' dynamic loading code malfunctions).

You can contact me by e-mail at

Links to libunicows

Libunicows is listed at, MinGW homepage.