A .key file is a presentation made in Apple Keynote. PowerPoint and Windows can't open it directly. Here are your options.
| Option | Cost | File leaves your PC? | Looks like the original? |
|---|---|---|---|
| 1. Ask for a PowerPoint or PDF copy | Free | No | Yes (PDF exactly) |
| 2. iCloud.com | Free, Apple ID needed | Yes, uploaded to iCloud | Yes |
| 3. A desktop iWork viewer | Free to view | No | Text and layout yes, background pictures may be missing |
| 4. Preview inside the file | Free | No | First slide only |
In Keynote the sender chooses File → Export To → PowerPoint or PDF. A PDF looks exactly like the original; a .pptx can be edited but some animations and fonts may change.
With a free Apple ID you can upload the file to iCloud Drive and open it in Keynote for iCloud in your browser, play the slideshow, or download it as PowerPoint or PDF. The file is stored on Apple's servers.
Our iWork File Viewer for Windows opens .key files on your PC with no Apple ID and no upload, showing each slide as a page. Viewing and copying text are free; Pro adds PDF and PNG export and printing. It does not play animations, and slide background pictures may be missing. The app tells you when that happens.
A Keynote file is a ZIP package. Copy it, rename the copy to .zip and open it to find a small preview image of the first slide.
No. PowerPoint can't read Keynote files. Ask for a .pptx export or use iCloud.com.
Yes, in a browser with Keynote for iCloud, or by converting it to PowerPoint first.
See opening Pages files and opening Numbers files on Windows.