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Deviare In-Proc is a code interception engine for Microsoft Windows® developed by Nektra Advanced Computing.

This library is at the core of our Deviare v2.0 and SpyStudio Application Monitor technologies. Deviare is an alternative to Microsoft Detours® but with a dual license distribution.

The library is coded in C++ and provides all the facilities required to instrument binary libraries during runtime. It includes support for both 32 and 64 bit applications and it implements the interception verifying different situations that can crash the process. If you need to intercept any Win32 functions or any other code, this library makes it easier than ever.

Unlike the rest of the libraries, Deviare In-Proc provides a safe mechanism to implement multi-threaded application API hooking. When an application is running, more than one thread can be executing the code being intercepted. Deviare In-Proc provides safe hooking even in this scenario.


To use Deviare In-Proc you must have the following:

  • IBM PC or compatible.
  • Microsoft Windows 2000 or later.
  • Visual Studio 2013 or later (with latest available Service Pack recommended).


Clone the repository using git clone --recursive. If you already cloned without the --recursive option, you can complete the repository initialization with git submodule update --init. If you download the zipped source code package instead, take note that this project depends on UDis86. You can open the NktHookLib.sln with Visual Studio to rebuild the libraries.

The LIBS subfolder contains precompiled libraries of the product.

To use the library in your project, add the reference to the NktHookLib.h file located in the INCLUDE folder and ensure to link with the correct library. The provided HookTest sample contains #pragma sentences you can use to tell the linker to add the libraries depending on the platform.


The new experimental feature of Deviare In-Proc is the ability to hook .NET methods and redirect them to your own. Feel free to examine the provided C# samples to see .net method hooking in action.


Although the library functionality remains the same, the code was modified to make it independent from Visual Studio's CRT libraries.

Deviare In-Proc base library only depends on NTDLL.DLL, no kernel32.dll nor any other library is used.

It also dynamically discovers needed apis in order to eliminate NTDLL.DLL static binding when used in an application or dll. This allows developers to use the library, for e.g., in custom dll's that will be injected in non-initialized processes that were launched in a suspended state.

The C ApiHook sample provided with this package was also modified in order to demonstrate how to build an executable with minimal imported api's. Since Visual Studio's compiler & linker inserts undesired Microsoft specific code and data, the sample contains some hacks and modified compiler switches to circumvent this behavior.


If you experience something you think might be a bug in Deviare In-Proc, please report it in this GitHub repository or write to us in our contact page.

Describe what you did, what happened, what kind of computer you have, which operating system you're using and anything else you think might be relevant.


This library has a dual license, a commercial one suitable for closed source projects and a GPL license that can be used in open source software.

Depending on your needs, you must choose one of them and follow its policies. A detail of the policies and agreements for each license type are available in the LICENSE.COMMERCIAL and LICENSE.GPL files.

For further information please refer to our licensing options or contact Nektra here.

This library uses a portion of UDis86 project, authored, copyrighted and maintained by Vivek Thampi. UDis86 is licensed under the terms of BSD License. For any questions referring to UDis86 contact the author at vivek[at]sig9[dot]com.