Why Adding Subtitles Without Uploading Matters
- Data Privacy: Your video files can contain sensitive content — personal moments, business meetings, client footage. Uploading to a server means trusting a third party with that data.
- Faster Processing: No upload or download wait times. Processing starts instantly because everything happens on your machine.
- No Server Dependency: Cloud services go down, have rate limits, and can change their terms. Browser-based tools just work — no account required.
- Works Offline: Once the page loads, you can process videos without an internet connection. Perfect for working on the go.
Drop Your Video File
Drag and drop any MP4, MOV, or MKV file. Your video stays on your device — nothing is uploaded anywhere. Open the Video Editor Tool and drop your file in.
AI Transcribes in Your Browser
OpenAI Whisper processes the audio and generates word-level captions. Edit text, adjust timing, pick a style — all without any data leaving your machine.
Export Locally
Your browser renders the final MP4 with captions baked in using WebCodecs. Download the file — no server involved. The entire pipeline runs on your device.
How Browser-Based Processing Works
No Cloud Upload
Unlike Veed, Descript, or CapCut online, your video file never touches a server. This means zero data privacy risk.
WebCodecs API
Modern browsers can encode H.264 video natively. We use this to render your captioned video at full HD quality, right on your machine.
OpenAI Whisper
The same AI model used by professional transcription services, running efficiently to process your audio for accurate captions.
Frequently Asked Questions
Does my video really stay on my device?
Yes, your video file is never uploaded to any server. All processing happens in your browser using WebCodecs and OpenAI Whisper. Your data stays entirely on your device.
How does AI transcription work without uploading?
Only a small audio extract is processed for transcription. The video file itself never leaves your device. Caption rendering and MP4 export happen entirely in your browser.
Is this tool free?
Yes, 100% free with unlimited exports and no watermarks.
What browsers are supported?
Works best in Chrome and Edge (Chromium-based browsers) which support WebCodecs for high-quality video export.