Open KEY File

KEY file extension is used to store files in Apple Numbers office application file format. Apple Numbers is a free application from Apple used to create and edit spreadsheets.

KEY file is a compressed archive containing various files which compose Apple Numbers Spreadsheet. But it is not recommended to open KEY file using Zip or any other unarchiver software. It is much better to use Apple Numbers software to open KEY file. If you don’t have Apple Numbers installed or you are running an operating system other than Mac OS you can either use a KEY file online conversion software or upload your KEY file to iCloud.com, open it in online Apple Numbers application, and download it as Microsoft PowerPoint PPTX file from there.

Apple Keynote is part of Apple iWork suite of application which includes:

Apple Pages. Document editing application.
Apple Keynote. Presentation application.
Apple Numbers. Spreadsheet application.

All Apple iWork applications are available for Mac OS and iOS. That means that any KEY, NUMBERS and PAGES file could also be easily opened on mobile devices with a compatible application. Also, iWork applications are available online via iCloud.com service. You can open KEY file online using iCloud.com and edit it online.

Open KEY File on Windows OS

Try double clicking on a KEY file in Windows File Explorer.
If the KEY file opener software capable of opening with KEY file is associated correctly then the file will open
If the file did not open you can read how to use Apple KEY files in Microsoft PowerPoint via iCloud.
If you are note able to use Apple iCloud you should install LibreOffice
To open KEY file in LibreOffice you need to launch it and then select File->Open in the main menu
In the File Open dialog select KEY file and click "Open"

open key file