Add subtitles to video — without uploading anything
Veed, Kapwing and Clideo upload your video to their servers before you can even start editing. BurnSub never does. Drop, caption, download — your file never leaves your device.
Upload comparison: BurnSub vs the rest
| Feature | BurnSub | Veed.io | Kapwing | Clideo |
|---|---|---|---|---|
| Upload required | ✗ | ✓ | ✓ | ✓ |
| Video stays local | Yes | No | No | No |
| Upload time (1GB) | 0 seconds | ~5 min | ~5 min | ~5 min |
| File size limit | None | 250 MB | 250 MB | 500 MB |
| Stores video on server | ✗ | ✓ | ✓ | ✓ |
| GDPR-easy by design | Yes | No | No | No |
Why "no upload" actually matters
- Privacy. Confidential client footage, internal company recordings, personal voice memos — these shouldn't sit on someone else's server.
- Speed. Uploading a 1 GB video on a 30 Mbps connection takes ~5 minutes. BurnSub starts processing in under a second.
- Reliability. No upload means no failed transfers, no "session expired" errors, no losing your work to a flaky connection.
- No file-size cap. Cloud tools cap free uploads at 250–500 MB. BurnSub has no cap because there's no server.
How can subtitle generation work without an upload?
Modern browsers support two APIs that changed everything:
- WebCodecs — gives the browser direct access to the GPU's video decoder and encoder. The same chip that plays YouTube can now process your file.
- WebGPU — runs neural networks like Whisper-Turbo (the same model behind ChatGPT's voice) on your local graphics card.
BurnSub uses both. Your video is decoded, captioned, styled and re-encoded entirely on your hardware. The browser tab is the workspace.
Is this really faster than uploading?
For most videos under 30 minutes, yes — by a large margin. A 5-minute 1080p clip captioned and burned in BurnSub takes about 60–90 seconds end-to-end on a 2022+ laptop. The same workflow in Veed takes 4–8 minutes including upload, cloud queue, and download.
What hardware do I need?
Anything that runs Chrome 113, Edge 113, Firefox 147 or Safari 17 works. WebGPU acceleration is preferred but not required — without it, captions just take longer to generate. Encoding works on any hardware that decodes H.264, which is essentially every laptop and phone made since 2018.
Does BurnSub track my video or its content?
No. The tool serves a static page from Cloudflare. There's no database recording your file, no analytics that capture content. Standard web analytics (page views, browser type) are anonymized. Your video doesn't touch our infrastructure.