A professional desktop subtitle editor with on-device AI transcription. Create, edit, and style subtitles with word-level timing precision — Descript-style editing for everyone.
Built with AI — This entire application was developed using Claude Code, Anthropic's AI coding assistant. From architecture decisions to implementation details, every line of code was written collaboratively with AI.
Tiny app, fully on-device AI — no cloud transcription, no setup
Download the latest .dmg from the Releases page, open it and drag OpenSub into your Applications folder.
Important
"OpenSub is damaged and can't be opened" — the app is not yet signed with an Apple Developer certificate, so macOS Gatekeeper blocks it with this (misleading) error. The app is fine; remove the quarantine flag once and it starts normally:
xattr -cr /Applications/OpenSub.appOpenSub is a macOS desktop app that automatically generates word-precise subtitles from video files and lets you style them like the big creator tools (karaoke highlights, boxes, glows) — then burns them pixel-perfectly into the video.
Since the Tauri rewrite (v1.0), transcription runs on NVIDIA Parakeet TDT 0.6b v3 directly inside the Rust backend via ONNX — roughly 35x realtime on Apple Silicon, supporting 25 languages with automatic detection. The app bundle is a few megabytes; the AI model (~670 MB) is downloaded once on first launch.
- Import — drag & drop any video
- Transcribe — Parakeet generates word-level timestamps in seconds
- Edit — fix text inline, retime on the waveform timeline, undo/redo everything
- Style — templates, fonts, karaoke box/glow, drag-positioning with snap guides
- Export — hardware-encoded MP4 with pixel-perfect burned-in subtitles
- ⚡ Fast on-device ASR — Parakeet TDT v3 (ONNX, int8), 25 languages, auto-detect
- 🎤 Speaker diarization (optional) — color subtitles per speaker
- 🌊 Waveform timeline — click-to-seek, drag blocks, retime via edge handles
- ↩️ Full undo/redo across all edits
- 🎨 Template gallery + style profiles (save/import/export)
- ✨ AI correction — Gemini (via OpenRouter) listens to the audio and proposes fixes with a reviewable diff
- 🎬 Pixel-perfect export — preview and export share the same renderer; VideoToolbox hardware encoding
- 🔄 Auto-updates via GitHub Releases
- 🌍 German & English UI
git clone https://github.com/ibimspumo/OpenSub.git
cd OpenSub/app
npm install
npm run tauri dev # requires: Rust toolchain + `brew install ffmpeg`See app/README.md for architecture details and release builds, and CLAUDE.md for the full codebase guide.
MIT