CLF File

What are CLF files and how to open them

Are you having problems opening a CLF 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 CLF files.

What is a CLF file?

CLF files have multiple uses, and ListPro Data is one of them. Read more about the other uses further down the page.

ListPro Data

These CLF files contain customized lists created in ListPro, a list creation program. These CLF files can be shopping lists, checklists, or any other list your heart desires.

How to open CLF files

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

While we have not verified the apps ourselves yet, our users have suggested ten different CLF openers which you will find listed below.

Last updated: August 31, 2026

All known file formats using extension .CLF

While ListPro Data is a popular type of CLF-file, we know of 2 different uses of the .CLF file extension. Different software may use files with the same extension for different types of data.

Source Insight Custom Language File

A Source Insight custom language file stores all the settings that define a user-added programming or textual language in Source Insight when the built-in options do not cover the needed syntax. It includes rules for syntax highlighting, parsing definitions of symbols (functions, variables, etc.), comment styles, case sensitivity, identifier characters, number formats, and other display and parsing behavior. Such a file is used by Source Insight to extend its language support.

This format is created and used by Source Insight. In version 3.x of the program, custom language definitions are stored in files with this format. Users can export a custom language from the Preferences → Languages dialog box, producing one of these files. They can also import such files later to reuse the same language settings in another installation or project.

The custom language file is written in a text-based format that encodes language properties including whether the language is case sensitive, whether it contains program source code, how comments and multiline ranges are defined, what keywords are used, and regular expressions for parsing custom symbol definitions. It defines how files of certain types (via wildcards or extensions) are associated with the custom language for syntax formatting and symbol parsing.

In version 4 and newer, Source Insight uses an updated version of custom language files with a different extension; this older format applies specifically to version 3.x.

Signature detail: the file begins with the byte sequence 0x11090000 at offset zero in its binary header.

Various apps that use files with this extension

These apps are known to open certain types of CLF files. Remember, different programs may use CLF files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about CLF file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.