Auto Subtitle Generator

Why captions decide whether your video gets watched

The majority of short-form video is watched without sound. People scroll in bed next to someone sleeping, on a bus, in a waiting room, at a desk. If your first sentence only exists in the audio, most of the feed never hears it — they just keep scrolling.

That is why every serious creator burns captions in. Not the platform's own auto-captions, which are unstyled, often wrong, and sometimes not shown at all, but captions that are part of the picture.

What makes captions readable

An outline, always. White text over a bright sky disappears. A dark outline around every letter keeps the words legible over anything, which is why the outline control here defaults to on rather than off.

Few words at a time. Two or three words per caption is the short-form convention. It forces the eye to move with the speech instead of reading ahead, and it keeps the text large enough to read on a phone held at arm's length.

A highlight on the spoken word. Colouring or enlarging the word currently being said is the single detail that makes captions feel professional rather than pasted on. It also genuinely helps comprehension — the eye knows where it is.

Room from the edges. Platforms overlay their own interface at the bottom and along the right side. Keep captions clear of the bottom fifth or the username and buttons will sit on top of them.

Why the automatic version still needs you

Whisper, the model this tool runs, is good — it punctuates, it capitalises, and it handles accents better than anything freely available a few years ago. It is not perfect. It will mishear proper nouns, brand names, technical terms and anything said over noise.

Which is exactly why every caption here is an editable box rather than a finished result. Fix the two words it got wrong, and the timing of the surrounding words is recalculated so the highlight stays in step. A tool that gives you an uneditable transcript is a tool that wastes your time the moment it makes a mistake.

SRT, VTT, or burned in?

Burn them in for TikTok, Reels and Shorts. Styled captions that are part of the picture always look better than the platform's own, and they cannot be switched off or rendered in some default font.

Use an SRT file for YouTube, where uploading subtitles separately means viewers can turn them on or off, and — importantly — Google can read them. Subtitles are indexed, so an SRT makes the video findable by what is said in it.

Use VTT if you are embedding the video on your own website with an HTML video player.

Nothing stops you doing both, and plenty of people do: burned-in captions for the visual, plus an SRT for the search engine.

About the one thing that is downloaded

This site's promise is that your files never leave your device, and that holds here: your video and its audio are never transmitted anywhere.

There is one honest asterisk worth stating plainly. The speech recognition model itself — around 80 MB — is downloaded to your browser the first time you use the tool, and cached afterwards. That is data coming in, in exactly the same category as a font or a JavaScript library. Your recording does not go out. Once the model is cached you can disconnect from the internet entirely and the tool keeps working, which is the simplest proof of the difference.

Every commercial captioning service works the other way round: your recording goes to their servers, gets processed on their hardware, and you are billed by the minute. That is why they cost money and this does not.