A KEY file is a presentation created by Apple Keynote, a macOS (OS X) and iOS program used to create presentations. It contains slides that may include text, images, shapes, charts, tables, transitions, audio, video, and notes. KEY files are stored in the Mac OS X package format and also store .XML data used by the presentation.

KEY file open in Apple Keynote 7 Keynote is one of Apple's three productivity apps that make up iWork, along with Pages and Numbers. These applications are Apple's versions of the more popular PowerPoint, Word, and Excel programs, which are developed by Microsoft and available in the Office suite. The iWork apps are developed for macOS and iOS but can also be accessed using a browser on a Mac or PC through iCloud. Keynote presentations can be used for academic, business, or personal purposes. You can choose to start your presentation from one of the templates provided with the program or from scratch. When you are finished creating your presentation you can share it directly from your device or through Keynote Live. You can also export a KEY presentation to another format such as .PDF, .HTML, QuickTime .M4V video, or as a .JPEG, .PNG, or .TIFF image. If you need to open it in Keynote '09 or earlier you can export it in that format, as well. But the most useful export option is to the PowerPoint format, either .PPTX or .PPT.

Software registration file used by LightWave, a professional 3D rendering application; stores the 16-digit license key and enables users to have a legal copy of the software.

For LightWave 10, licenses are saved to the following directories: Windows: [user]\.NewTek\LightWave\10.0\licenses\ Mac OS X: [user]/Library/Application Support/NewTek/LightWave/10.0/licenses/

A KEY file is a file used to contain registration information or a security code for a software program. It is often created when the program is registered and typically stored in the program's application folder or the system preferences folder.

A KEY file is a generic file extension used by various programs when registering legal copies of the software. It may be saved in a plain text format but generally contains some form of encrypted key string that authenticates the purchase and registers the software.

Since KEY files are used by various software products, no single program will be able to open them. Instead, you will have to know which program a KEY file corresponds to in order to use it to register the software.