CLW File

What are CLW files and how to open them

Are you having problems opening a CLW file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CLW files.

What is a CLW file?

A .CLW file is a MFC ClassWizard Info file.

MFC ClassWizard Info files store metadata used by the Visual C++ ClassWizard in Microsoft's MFC (Microsoft Foundation Classes) framework to automate creation and maintenance of C++ classes, dialog data exchange, message handlers and related class‐resource mappings. These files are generated by Visual C++ when working on an MFC project and are updated as new classes or resources are added, or when custom DDX/DDV routines are defined. They enable the ClassWizard feature to interpret and display class hierarchies, message maps, resource identifiers, and file paths without needing to parse all source code on the fly.

The program that writes these files is Visual C++, specifically the ClassWizard component of Microsoft's MFC development tools. Visual C++ reads the file when opening a project in ClassWizard to display class count, list of classes, resources, include directives, base classes, and related file names. When the .clw file is missing or deleted, ClassWizard can rebuild it by scanning header (.h), implementation (.cpp), and resource (.rc) files for special annotations ("ClassWizard special‐format comments") used in source to mark class and function declarations.

The file format is plain text, structured into numbered sections and key‐value pairs. A typical file begins with the signature ; CLW file contains information for the MFC ClassWizard followed by sections such as [General Info], with entries like Version, LastClass, ClassCount, ResourceCount, etc. Class sections use markers like [CLS:ClassName] listing properties such as HeaderFile, ImplementationFile, BaseClass, Type, and Filter. The format also supports an [ExtraDDX] section for custom dialog data exchange/validation routines.

How to open CLW files

Important: Different programs may use files with the CLW file extension for different purposes, so unless you are sure which format your CLW file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 31, 2026

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