Private by design
Add captions without uploading your video.
Your video file never leaves your device — not to caption it, not to export it. Only the audio is used to work out the words.
Uploading a video to a caption service means handing over the whole file, which is slow on large masters and a problem for anything confidential. LumaCaption never uploads your video: the file stays on your device, and only the extracted audio is sent for transcription.
Almost every caption tool works the same way: you upload your footage to their cloud, their servers process it, and you trust their retention policy. That’s a non-starter for client work under NDA, unreleased product footage, interviews, family videos — or just anything you’d rather keep to yourself.
LumaCaption never asks for your video. The file you pick stays on your device, the captioned version is written back to your device, and the only thing needed to find the words is the audio. There’s no upload step for your footage at all — which also means no waiting for a 2 GB file to crawl up your connection before work can even begin.
Your video never leaves
A file can’t leak from a server it never reached. Your footage stays with you; only the audio is used for transcription, and we store just your account, plan and usage.
Safe for client and NDA work
Caption confidential footage without handing the footage itself to anyone.
Big files start instantly
With nothing to upload, a 2 GB 4K file starts transcribing in seconds — the wait most tools call “processing” simply doesn’t exist.
Exports stay local too
The captioned video is put together on your device and saved straight to disk. Nothing round-trips through us.
What actually leaves your machine
Being precise about this matters more than a reassuring adjective, so here is the whole of it. Your **video file is never uploaded** — not to transcribe it, not to preview it, not to render it. It is opened locally, decoded locally, and the burned-in export is rendered locally on your own device.
Transcription is the one step with a choice. Candy Lite and Candy Ultra both send the **extracted audio track** — not the picture — to be transcribed and return the words and their timings. If audio leaving the device is itself the problem, that is the thing to weigh; if it is the footage that is sensitive, the footage never moves.
Why no-upload is faster, not just safer
Upload time is the hidden cost of every cloud caption tool, and it scales with your file rather than with your video. A 2 GB 4K master on a typical Indian home connection is a long wait before any work starts, and it happens again every time you re-cut. Audio is one to two orders of magnitude smaller than the video it came from, so extracting and sending only that turns a multi-minute upload into a few seconds.
Rendering locally removes the second queue. A cloud tool renders your export on a shared machine, which means waiting behind other people’s jobs at busy times. Local rendering is bounded only by your own device, which is also why re-exports cost nothing here — there is no per-render bill to pass on.
When this is the deciding factor
For a lot of creators, no-upload is a speed feature and nothing more. For some work it is the only thing that makes the tool usable at all: unreleased client footage, anything under an NDA, interview material where the subject consented to one use, internal training video, and medical or legal recordings.
The practical test is simple — if uploading the footage to a third party would require someone’s permission, a tool that never uploads it removes the question rather than answering it.
What travels, step by step
| Step | Runs where | What leaves your device |
|---|---|---|
| Opening and decoding the video | Your device | Nothing |
| Transcription | Cloud | Extracted audio only |
| Styling and preview | Your device | Nothing |
| Burned-in export | Your device | Nothing |
| SRT / VTT / TXT download | Your device | Nothing |
How it works
Open the editor and pick a file
Your video is read straight from disk — watch your network tab: there’s no upload.
Get your words, timed
Candy Lite is free and unlimited on paid plans; Candy Ultra spends minutes for our sharpest Hindi, Hinglish and English. Either way, only the audio is involved.
Render and save locally
The captioned video is composed on your device and saved straight to disk.
Common questions
How can it caption a video without uploading it?
Captions only need to know what was said and when — that comes from the audio, not the picture. LumaCaption reads your file where it sits, works from the audio alone, and writes the finished video back to your device.
Is anything sent to your servers at all?
Your account and billing data, and — with Candy Ultra — the extracted audio for transcription. Your video file is never uploaded, and the captioned export is never uploaded either.
Is it slower than tools that upload?
Usually faster in practice. Captions start appearing progressively while transcription is still running, and you skip the upload wait entirely — for large files that’s often the slowest step of a cloud tool.
Do I need a fast connection?
Not for your footage — it never travels. You’ll want to be online to sign in, to start an export and to use Candy Ultra, but none of that depends on your upload speed the way a cloud caption tool does.
