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Software components for data protection, secure storage and transfer


Instant control over file and folder operations in Windows and .NET applications

CallbackFilter lets you monitor and control disk activity, track file and directory operations (create, read, write, rename etc.), alter file data, encrypt files and much more...

CallbackFilter is a component for use in software development for Windows® platform.

Clients say:

On-the-fly encryption of data provided by your CallbackFilter component came very handy.

Latest version

Release:  4.1.104
20 September 2016

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Technical Specification


CallbackFilter is a software development kit for Windows applications, which tracks any file requests on-the-fly. Your user-mode application gets notification (callback) when a file operation is executed. Besides simple notifications, CallbackFilter lets your application decide how to process a request: whether modify input or output data before or after the request is performed or even cancel the request. Key functionality of CallbackFilter includes:

  1. Synchronous callbacks on all main filesystem requests (file create/open, read/write, seek, get information, close, delete, rename, enumerate directories)
  2. Asynchronous notifications on all main filesystem requests
  3. Per-process filtering of file and directory access (possibility to allow or forbid access based on process and owner information)
  4. Synchronous callbacks on path reparsing (these callbacks let you change path to the file being accessed thus redirecting the request)
  5. Creation of virtual files and directories on existing filesystems
  6. Possibility to setup access rules that will be used during system boot (i.e. when the application is not running)


CallbackFilter consists of the system-level filesystem filter driver and user-mode API.


File System Filter driver intercepts various requests going to the file system. If the request matches one of the rules, specified by the application, the driver performs the action defined by the rule. The action can be to process or decline the request unconditionally and to call the callback function in your application synchronously or asynchronously. Your callback can also decline or allow the request, perform the request itself (not passing it further) or post-process the request.

User-mode API

User-mode API is simple and introduces about ten functions, specific to driver management and storage mounting operations. Also the API includes about 20 callback functions (events) which your application can handle to get notified about different types of file system requests.
The API is used to activate the filter and to set the callback rules.

User-mode APIs are provided for .NET, VCL and C++.

Miss a feature? Tell us about your idea using Wish List.

Supported platforms

  • Windows:
    • Windows 10
    • Windows 2012 Server R2
    • Windows 8.1 (32-bit and 64-bit)
    • Windows 2012 Server
    • Windows 8 (32-bit and 64-bit)
    • Windows 2008 Server R2 (32-bit, 64-bit AMD64 and 64-bit Itanium)
    • Windows 7 (32-bit, 64-bit AMD64 and 64-bit Itanium)
    • Windows 2008 Server (32-bit, 64-bit AMD64 and 64-bit Itanium)
    • Windows Vista (32-bit, 64-bit AMD64 and 64-bit Itanium)
    • Windows 2003 Server (32-bit, 64-bit AMD64 and 64-bit Itanium)
    • Windows XP (32-bit, 64-bit AMD64 and 64-bit Itanium)
  • Microsoft .NET Framework on Windows:
    • .NET 4.6.x (32-bit and 64-bit)
    • .NET 4.5.1 (32-bit and 64-bit)
    • .NET 4.5 (32-bit and 64-bit)
    • .NET 4.0 (32-bit, 64-bit x64 and Itanium)
    • .NET 3.5 (32-bit, 64-bit x64 and Itanium)
    • .NET 3.0 (32-bit, 64-bit x64 and Itanium)
    • .NET 2.0 (32-bit, 64-bit x64 and Itanium)

Development tools

  • .NET API:
    • Visual Studio 2015
    • Visual Studio 2013
    • Visual Studio 2012
    • Visual Studio 2010
    • Visual Studio 2008
    • Visual Studio 2005
    • CodeGear Prism
  • C++ API:
    • Visual Studio 2015
    • Visual Studio 2013
    • Visual Studio 2012
    • Visual Studio 2010
    • Visual Studio 2008
  • VCL API (VCL units are linked into the application without any external DLLs):
    • Embarcadero RAD Studio 10.1 Berlin
    • Embarcadero RAD Studio 10 Seattle
    • Embarcadero RAD Studio XE8
    • Embarcadero RAD Studio XE7
    • Embarcadero RAD Studio XE6
    • Embarcadero RAD Studio XE5
    • Embarcadero RAD Studio XE4
    • Embarcadero RAD Studio XE3
    • Embarcadero RAD Studio XE2
    • Embarcadero RAD Studio XE
    • Embarcadero RAD Studio 2010
    • CodeGear RAD Studio 2009
    • CodeGear RAD Studio 2007
    • Delphi 10.1 Berlin (Win32 platform)
    • Delphi 10 Seattle (Win32 platform)
    • Delphi XE8 (Win32 platform)
    • Delphi XE7 (Win32 platform)
    • Delphi XE6 (Win32 platform)
    • Delphi XE5 (Win32 platform)
    • Delphi XE4 (Win32 platform)
    • Delphi XE3 (Win32 platform)
    • Delphi XE2 (Win32 platform)
    • Delphi XE
    • Delphi 2010
    • Delphi 2009
    • Delphi 2007
    • Delphi 2006
    • Delphi 2005
    • Delphi 7
    • C++Builder 10.1 Berlin (Win32 platform)
    • C++Builder 10 Seattle (Win32 platform)
    • C++Builder XE8 (Win32 platform)
    • C++Builder XE7 (Win32 platform)
    • C++Builder XE6 (Win32 platform)
    • C++Builder XE5 (Win32 platform)
    • C++Builder XE4 (Win32 platform)
    • C++Builder XE3 (Win32 platform)
    • C++Builder XE2 (Win32 platform)
    • C++Builder XE

Miss a feature? Tell us about your idea using Wish List.

To request more details please use our feedback form or Web-based Helpdesk system.

Ready to try? Download your own copy to try CallbackFilter for free. Ready to pull the trigger? Refer to the Prices and Ordering page for complete licensing information.


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As of July 15, 2016 EldoS Corporation will operate as a division of /n software inc. For more information, please read the announcement.

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