CIR File

What are CIR files and how to open them

Are you having problems opening a CIR 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 CIR files.

What is a CIR file?

A .CIR file is a Micro-Cap 5 Circuit file.

Micro-Cap 5 Circuit files hold the full definition of an electronics schematic as used in the Micro-Cap series of circuit simulation tools from Spectrum Software. They describe both how the circuit looks (the components, wiring, layout, fonts, colors, grid, windows) and how it is to be analyzed (AC, DC, transient analysis, stepping, limits, optimization etc.).

These files are created (written) by Micro-Cap when a user builds or edits a schematic in its editor. When loaded, Micro-Cap reads them to display the circuit diagram and to know what simulations to run. They also embed any custom component or shape definitions so the schematic file alone contains everything needed to view and simulate, even on another installation.

Internally these are plain text files tagged with many section headers that begin with "* ", such as " TRANSIENT ANALYSIS MONITOR ", " COMPONENTS ", " SCHEMATIC OPTIONS ", " GRID TEXT *". They typically include vendor strings like "SPECTRUM SOFTWARE" and version tags like "MICRO-CAP V". Byte-level signatures include specific bytes at set offsets (for example byte 0x35 at offset 0, byte 0x2A at offsets 41 and 52, a CR-LF at offset 56, etc.), though those are mainly for identifying the file type.

How to open CIR files

Important: Different programs may use files with the CIR file extension for different purposes, so unless you are sure which format your CIR 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 CIR 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 CIR files. Remember, different programs may use CIR files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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