No upload · No watermark · No minute quotas
Add subtitles without uploading your video
Every cloud caption tool starts with an upload — your footage lands on their servers, subject to their terms. CaptionForge is built the other way: the Whisper model downloads to your device once, and your video is transcribed, styled and burned in inside the browser tab. Not "we delete it after processing" — we never receive it. You can verify that claim yourself in two minutes.
- Footage never leaves your device — transcription and export are local
- Verifiable: watch DevTools' Network tab, or run in airplane mode
- NDA-compatible by architecture, not by policy promise
- Models cached on first load — works offline afterwards
How it works
- 1 Open DevTools (F12) → Network tab, or disconnect from the network after this page loads.
- 2 Drop a video — transcription runs; the Network tab shows no upload.
- 3 Style, edit and export the MP4 — still no traffic carrying your footage.
- 4 That's the proof. It works in airplane mode because there's nothing to send.
Frequently asked questions
How do I verify nothing uploads?
Two ways. Easy: load the page, then turn on airplane mode — transcription and export still work, which is only possible if everything is local. Thorough: open DevTools' Network tab while captioning; you'll see the model download (first visit only) and page assets, and zero requests carrying your video data.
Is this safe for client footage under NDA?
This is the architecture NDAs want: the footage is never disclosed to a third party because it never leaves your machine. With cloud tools you're trusting a policy document; reviewers explicitly warn agencies to recheck terms before uploading sensitive client footage to caption services. Here there's no policy to trust — there's no upload.
How does this compare to CapCut's terms?
CapCut's June 2025 terms of service grant ByteDance a perpetual, irrevocable license to user uploads — including likeness and voice, and even unpublished drafts — and that language hasn't been walked back. Our terms can be one sentence: we can't use your content, because we never receive it.
What network traffic does happen?
First visit: the page itself plus the Whisper model (about 200MB, size shown before download, cached after). If you buy Studio, a license-key check. That's it — no analytics on your footage, no thumbnails, no "processing telemetry". Your media files generate zero outbound traffic.
Can I use it fully offline?
Yes — after the first load the model is cached on your device, so you can caption footage with no network at all. Useful on set, on planes, and as a standing proof of the privacy claim.
Where do brand fonts I upload go?
Nowhere — same rule as footage. A Studio brand font (.ttf/.woff2) is stored locally in your browser's storage and used by the local renderer. It's never transmitted.