CKT File

What are CKT files and how to open them

Are you having problems opening a CKT 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 CKT files.

What is a CKT file?

CKT files have multiple uses, and Calamus Command-Key Settings is one of them. Read more about the other uses further down the page.

Calamus Command-Key Settings

Calamus Command-Key Settings stores the custom keyboard shortcuts and macro bindings that users define in the Calamus desktop publishing software. It captures which keys, possibly combined with modifiers like Control or Alt, trigger specific commands or sequences of actions ("macros") in the Calamus user interface.

Files in this format are written by Calamus SL (for example version 2003 R2 and newer) when the user changes the default key bindings or creates custom macros, and uses the "Save settings" or equivalent option in the Options or System Parameters menus. When loaded, Calamus reads this file to apply those custom key assignments so that keyboard and mouse input outside document windows invoke the user's mappings.

Calamus SL includes a default command-key settings file named DEFAULT.CKT, which provides the factory default shortcut layout; if the user creates their own, the custom file is usually named CALAMUS.CKT. Older versions replace DEFAULT.CKT when saving new layouts.

Command-Key Settings files begin with a fixed ASCII header "CALAMUSCKT" at the very start of the file (offset 0).

How to open CKT files

Important: Different programs may use files with the CKT file extension for different purposes, so unless you are sure which format your CKT 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 CKT openers which you will find listed below.

Last updated: August 31, 2026

All known file formats using extension .CKT

While Calamus Command-Key Settings is a popular type of CKT-file, we know of 4 different uses of the .CKT file extension. Different software may use files with the same extension for different types of data.

CircuitMaker Schematic

CircuitMaker 2000 schematic files store the electronic circuit diagrams created in the CircuitMaker virtual electronics laboratory. These represent the schematic diagrams showing components (resistors, transistors, power supplies, ground symbols, etc.), how those components are connected via wires and nets, and various annotation labels (designation, value, node names).

These schematic files are saved by the CircuitMaker software when designing or editing a circuit. Users draw the circuit, place devices, set up nets, add labels and symbols, and then "save" or "save as" to produce one of these schematic files. They can be reopened later for further editing, simulation, or to export netlists that tools downstream (such as PCB layout or SPICE simulation) use.

The files are in a proprietary text-based format used by CircuitMaker 2000. They begin with the ASCII header signature CircuitMakerText followed by a line break. That signature serves to identify that the file is in this schematic format.

Combinatorial Circuit Worksheet Project

We know that one CKT format is Combinatorial Circuit Worksheet Project. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

LogicLab Explorer Circuit Description

We know that one CKT format is LogicLab Explorer Circuit Description. We have not yet analyzed in detail what these files contain and what they are used for. We're working on it.

Various apps that use files with this extension

These apps are known to open certain types of CKT files. Remember, different programs may use CKT 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 CKT file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.