ASY File

What are ASY files and how to open them

Are you having problems opening an ASY 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 ASY files.

What is an ASY file?

An .ASY file is a LTSpice Symbol file.

LTSpice symbol files define how a component looks in LTSpice schematics, specifying its shape, pins, and default labels. Analog Devices' LTSpice writes these files when symbols are created - either by the user or automatically from subcircuit definitions - and uses them when rendering symbols in schematic (*.asc) files. These definition files are good for seeing or customizing how a component's electrical connection points (pins) are arranged, what name labels appear by default, and how the component body is drawn.

The symbol definition file has plain text with multiple lines, each beginning with a keyword and followed by parameters. It sets a version number, identifies whether the symbol is a "standard component" (CELL) or a hierarchical block diagram (BLOCK), draws the symbol's body using graphic primitives (lines, rectangles, arcs, circles), and sets up default positions for attributes like instance name and component value. It also defines pins: where they are placed, how their labels align, and their order in netlist generation. When a schematic references a symbol, LTSpice reads its symbol definition file to know how to draw the component and where to connect wires.

Version 4 symbols start with lines like "Version 4" and "SymbolType CELL" or "SymbolType BLOCK". Graphic elements typically use lines with a style keyword (often "Normal") and coordinate pairs. Labels use WINDOW entries, and pin definitions use a PIN line followed by PINATTR lines such as "PinName" and "SpiceOrder". One signature of this format is the presence of "PINATTR PINNAME", the keyword "SYMBOLTYPE", the term "VERSION" on the first line (e.g. Version4 starting at byte 0), and the keyword "NORMAL" in graphic element lines.

How to open ASY files

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

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

Last updated: August 22, 2026

Various apps that use files with this extension

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