CFN File

What are CFN files and how to open them

Are you having problems opening a CFN 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 CFN files.

What is a CFN file?

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

Calamus Font Data

Calamus Font Data files store vector outline fonts designed for use in the Calamus desktop publishing system, a program developed by invers Software originally for Atari ST and later Windows. These files hold shapes of the font's characters (glyphs), kerning information, and other metadata needed by Calamus to render text, especially for high-resolution print and layout work. CFN fonts use no hinting.

Files in this format are written by invers Software's Calamus or its modules (for example Calamus SL) when creating or exporting fonts, or when converting imported TrueType or PostScript fonts into the native format. Calamus reads CFN fonts to display and print text, perform layout, apply vector scaling, and automatically manage kerning even between characters from different fonts or sizes.

Glyph outlines in CFN use straight lines and Bezier curves mapped to a high-resolution vector grid (16 384 × 16 384 units). Kerning is stored in two ways: standard kerning pairs and "stair-step" kerning on each character's left and right edges across eight vertical levels. There is no hinting. The format begins with the ASCII signature "CALAMUSCFN" in the first ten bytes.

How to open CFN files

Important: Different programs may use files with the CFN file extension for different purposes, so unless you are sure which format your CFN 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

All known file formats using extension .CFN

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

The Bat! Accounts Configuration

The Bat! Accounts Configuration files store settings and template data used by the email client The Bat! from Ritlabs. These files are written by The Bat! when configuring individual email accounts, or when capturing shared-folder settings, message templates, and macro definitions per account. They are consumed by The Bat! during startup and whenever the user edits account properties or templates, ensuring that display names, From/Reply-To fields, signature and template macros, message filtering information and folder behavior for each account are preserved.

Internally the files are in a binary format that is not publicly documented. A common instance is named ACCOUNT.CFN and appears inside each account's subfolder in the "Mail" directory; another copy named ACCOUNT.CFN in the root of the Mail directory holds settings for shared folders not tied to any single account. The Bat! reads these files together with other account configuration files to rebuild an account's configuration and template data. These files are not meant to be edited by hand, because incorrect changes can lead to corruption or unexpected behavior.

These configuration files can also include template macros such as %ATTACHMENTS, %OFROMADDR, %SUBJECT, %CURSOR, and many others, which are placeholders used inside message and signature templates that The Bat! replaces at runtime. They may also contain fixed byte signatures like 0x020000 at offset 1 and 0x00000100000000000000 at offset 7 to help the program recognize valid configuration files.

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!

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 CFN file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.