CIRC File

What are CIRC files and how to open them

Are you having problems opening a CIRC 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 CIRC files.

What is a CIRC file?

A .CIRC file is a Logisim Circuit file.

Logisim Circuit files store electrical logic circuit designs as XML documents. They are produced by the software Logisim (and its maintained successor, Logisim-evolution) in order to describe digital circuits - gates, wires, memory elements, and how these components are arranged - for editing, simulation, and sharing. These files let circuit designers build, test, and visualize both combinational and sequential logic in a graphical environment.

When a circuit is saved, the software writes out all details needed to fully reconstruct the design. This includes components' types (e.g. AND, OR, NOT gates, flip-flops), their locations and orientations on a grid, the wires connecting component terminals, settings for simulation parameters, libraries used, toolbars and mappings for mouse tools, and which sub-circuit is the main one. In the case of Logisim-evolution, hierarchical designs and support for additional features such as HDL-backed components are included.

Internally, these files are plain text XML encoded in UTF-8. The root element is <project> with attributes for the Logisim version that wrote the file. Within it are child elements such as <lib> (library declarations), <main> (which circuit is the main one), <options> (simulation limits, randomness, etc.), <toolbar>, <mappings>, and one or more <circuit> elements defining each subcircuit. Components are represented by <comp> elements with attributes and nested <wire> elements connecting them.

Files of this format can be recognized by a combination of markers: they begin with an XML declaration such as <?xml version="1.0" encoding="UTF-8"?>, contain header lines like "THIS FILE IS INTENDED TO BE LOADED BY LOGISIM", and include keywords like CIRCUIT NAME, TOOL NAME, AND GATE, OR GATE, NOT GATE, MAIN NAME, and elements such as COMP LIB, TOOL LIB, OPTIONS and mappings for tools and gates.

How to open CIRC files

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

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

Last updated: August 31, 2026

Various apps that use files with this extension

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