Opening CFB Files

The CFB file type is primarily associated with Microsoft Office Word.

CFB	File extension: CFB
	File type:	Binary container

What is a CFB file?

CFB files mostly belong to Microsoft Office Word. CFB files use the Compound File Binary format.: This file format is a binary container that holds multiple data streams in one file. It is used to store structured content such as text, images, and embedded objects all together.
Use cases include:

Microsoft Office Documents: Many Office files (like those created by Word and Excel) use this format to package document data. Visit Microsoft Office Word for more details.

Lighting Fixture Libraries: Some CFB files contain data for lighting systems, as in the CAST Lighting Fixture Library, a format used in WYSIWYG design.

Forensic Analysis: Certain files, linked with Case Forensics Browser and related projects, rely on this compound structure for keeping digital evidence organized.

Machine Data Storage: A few files store machine-specific data—for example, Cubicreator bonding machine data files used in engineering applications. More information is available at Cubicreator.

FilExt.com tip: This architecture acts like a mini file system within a file, allowing efficient access to a range of data types.

How to open CFB files

You need a suitable software like Microsoft Office Word to open a CFB file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your CFB file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a CFB file directly in the browser:. Just drag the file onto this browser window and drop it.

Online CFB Text Viewer

Choose your .cfb file to analyze

or drag and drop it here

Online File Viewer

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CFB file extension format:

The file format, which is the arrangement and type of data in a file, determines which program can open the file. A file format is determined by the file extension and signature, so JPEG images have the extension .jpg and the first bytes in the file are ÿØÿ. If the file extension does not match the file format, double-clicking on the file will cause an error upon opening. If there are problems opening a file, you must first determine the file format used. Our evaluation of the CFB files is as follows:

CFB is not a common file extension and includes different formats for the applicable programs. The file formats most commonly found in CFB files are:

• 30% of all CFB files use the Microsoft Compound File format, which is also known as Compound File Binary File format (CFBF or CFB) or OLE2 Compound Document format. Compound document files are used to structure the contents of a document in the file. It is possible to divide the data into several streams, and to store these streams in different places in the file. In this way compound document files support a complete file system inside the file, the streams are like files in a real file system, and the sections are like subdirectories. The file signature of compound files is defined as D0 CF 11 E0 A1 B1 1A E1, so the first character of a file looks like "DOCFILE". Each CFB file has an application name, which is Microsoft Office Word. The globally unique identifier of this file type is 00020906-0000-0000-c000-000000000046 or 000c1084-0000-0000-c000-000000000046. Sections and streams in the file are named SummaryInformation, CompObj and DocumentSummaryInformation. The files are 4 KB to 6 MB in size, with a median of 51 KB. The file type was developed only in the last few years. A usual file name is secret.cfb or file20180601.cfb.
• 25% of all CFB files use the same file format, which can be identified by the letters "Library data file" at the beginning. They consist of unreadable binary data. The files are 3 KB to 73 KB in size, with a median of 17 KB. The files contain the following words: All rights reserved, CAST Group, CAST Group of Companies Inc, Companies Inc, rights reserved, Content originally, Content originally created by CAST is subject to Copyright and Library data file/Header v3.00/Content v3.20.

All other CFB files (45%) have no uniform format. If you want to find out which format your CFB file belongs to, just click on the button "Choose your .cfb file to analyze".