KEY (.key)

Overview

KEY is the native file format for Apple Keynote, Apple's presentation application for macOS, iOS, and iPadOS. Introduced with Keynote 1.0 in 2003, the KEY format has evolved significantly. Modern KEY files (from Keynote 6.0 onward) are ZIP archives containing protobuf-encoded binary data and assets. Earlier versions used a different format.

Keynote is known for producing visually polished presentations with smooth, cinematic animations that are difficult to replicate in PowerPoint. KEY files are tightly integrated with Apple's design system and export cleanly to PPTX, PDF, and movie formats when sharing with non-Apple users.

Common Uses

• Mac and iPad presentations — the default choice for Apple device users
• Design-focused decks — presentations that prioritise visual quality and animation smoothness
• Apple conference talks — many major Apple-ecosystem conferences use Keynote
• Academic presentations — popular among researchers and educators using Mac

Advantages

• Superior animations — Magic Move and other Keynote-exclusive transitions have no PowerPoint equivalent
• iCloud collaboration — real-time co-authoring across Mac, iPhone, iPad, and browser
• Export flexibility — exports to PPTX, PDF, HTML, movie, and image formats
• Apple Silicon performance — renders complex animations smoothly on M-series chips

Limitations

• macOS/iOS only for full features — Windows users cannot open KEY files natively; must export to PPTX first
• No cross-platform native app — Keynote for iCloud (web) provides limited feature access
• Animation loss on export — Magic Move and Keynote-specific transitions do not survive PPTX export
• Proprietary format — no official third-party native KEY editors exist

Supported Software

• Full support: Apple Keynote (macOS, iOS, iPadOS, iCloud web)
• Limited: Microsoft PowerPoint (can import KEY via iCloud export to PPTX)
• Conversion: Keynote's built-in export to PPTX, Google Slides (import PPTX version)