KzSubs
Local-First Subtitle Editor
KzSubs is a local-first subtitle editor for iPhone and Apple silicon Macs. Import a video, run speech recognition on-device with WhisperKit, review and edit captions in a timeline, style the subtitles, and export either a subtitled video or an SRT file. All processing happens locally on your device.
Screenshots
Welcome Screen
Timeline Editor
Styling
Subtitle Preview
Features
On-Device Transcription
Uses WhisperKit for speech recognition that runs entirely on your device. No data sent to external servers.
Advanced Editing
Edit captions at phrase and word-level. Interactive timeline lets you click to jump to any position.
Styling & Customization
Customize colors, fonts, and subtitle appearance. Drag-and-resize subtitles directly on the preview.
Multiple Export Options
Export as a subtitled video or as an SRT subtitle file. Auto-save projects for easy recovery.
Flexible Import
Import videos from Photos, Files, or Finder. Works seamlessly on iPhone and Mac.
Private & Local
All processing happens on your device. No cloud uploads. Your content stays with you.
How It Works
Import Your Video
Select a video from Photos, Files, or Finder on your iPhone or Mac.
Automatic Transcription
WhisperKit runs speech-to-text on your device. Keep the app in the foreground while the model downloads and processes.
Edit & Style
Review captions in the timeline. Edit at word or phrase level. Customize colors, fonts, and positioning.
Export & Share
Export a subtitled video or SRT file. Save your project for future editing.
Technical Details
Built With
- • SwiftUI
- • WhisperKit (speech recognition)
- • AVFoundation (video processing)
- • Core Data (project persistence)
Supported Platforms
- • iOS (iPhone)
- • macOS (Apple silicon M-series)
- • Mac Catalyst
Project Structure
KzSubs/
├── App/
├── DesignSystem/
├── Features/
├── Models/
└── Services/
Requirements
• macOS on Apple silicon (M-series or newer)
• Xcode for development
• An iPhone for iOS testing
• Note: Subtitle translation currently supports speech-to-English when enabled. Large local model downloads should be completed while the app stays in the foreground.
Important Notes
This is a work in progress. The app is functional but under active development.
All transcription and processing happens locally on your device using WhisperKit. Your video content never leaves your device.
Build artifacts are available at:
- • iOS: /build/ios-export/KzSubs.ipa
- • Mac: /build/mac-catalyst-export/KzSubs.app
Ready to Explore?
Check out KzSubs on GitHub and start creating subtitled videos with complete privacy.