.asy is Asymptote Module
Key Features: .ASY File Extension
What is an .ASY file?
The asy file extension is associated with LTspice IV, a high performance SPICE simulator, schematic capture and waveform viewer for Apple Mac OS X (macOS) and Microsoft Windows developed by Linear Technology Corporation.
The asy file stores circuit diagram data.
An asy file extension is related to the LTspice IV circuit diagram file format.
How to open:Use LTspice IV to open *.asy files.
How to convert:Probably can be converted to other formats.