Question 1

Is my video uploaded to a server?

Accepted Answer

No. The video is decoded, captioned and re-encoded in your own browser, so it never leaves your machine. The only network request the app makes is downloading the speech-recognition model, and only if you choose to transcribe.

Question 2

What does burning in captions mean?

Accepted Answer

Burned-in (or open) captions are drawn onto the video frames themselves, so they cannot be switched off by the viewer. That is what you need for social feeds and players that ignore separate subtitle tracks. You can also export a normal SRT or VTT subtitle file instead.

Question 3

Which video formats are supported?

Accepted Answer

MP4, WebM, MOV and MKV can be loaded. Export is MP4 (H.264) or WebM (VP9), depending on what your browser can encode.

Question 4

Do I need an account or a subscription?

Accepted Answer

No. There is no sign-up, no account and no cost. Open the page and load a video.

Question 5

Can it add captions to a TikTok, Reels or YouTube Shorts video?

Accepted Answer

Yes. Transcribe the speech, pick the karaoke style to highlight each word as it is spoken, and burn the captions in. Safe-area guides show where each app's own interface covers the picture, so a caption is never hidden behind a button.

Question 6

Can it translate subtitles into another language?

Accepted Answer

Yes. A translation model runs in your browser and writes the result into a new caption track, keeping the original timing. Nothing is sent to a translation service, so it can be used on confidential material.

Question 7

Is it free and open source?

Accepted Answer

Yes. The editor is free to use with no account, and the source is published on GitHub so it can be read, self-hosted or modified.

Question 8

Does it work offline?

Accepted Answer

Yes. It installs as a progressive web app and the editor runs with no network at all. Only the optional speech-recognition and translation models need downloading once, after which the browser caches them.

SeeB4 CC Editor