How are the captions so well-timed?

We transcribe your audio and run a second pass that pins every spoken word to a precise timestamp — usually within 100 milliseconds of the actual mouth movement. That's what lets captions highlight one word at a time as the speaker says it.

Does my video leave my device?

No. We only send a small piece of the audio to our servers — just enough to generate the transcript. Everything else happens inside your browser: playback, caption styling, and creating the final video. The original video never leaves your device.

Can I edit the AI-generated captions?

Yes — click Edit transcript after the captions load. You can fix a misheard word, adjust timing, add a missed word by typing in a gap, or delete an extra one. Changes show up in the preview live, so the exported MP4 matches exactly what you see.

How long can the video be?

Under 5 minutes works well on a modern laptop. Longer clips or high-resolution video take progressively longer and may slow your browser. As a rule of thumb, expect the export to take roughly 2–3× the length of the clip. A 1-minute video is typically ready in 2–4 minutes.

Can I translate captions to another language?

In the Auto-Captions editor, captions stay in the source language. To get English captions from non-English audio, use the Transcribe tab in Translate mode first — copy the English text back in, or export SRT from there and import into a video editor of your choice.

What formats are supported?

Upload: MP4, MOV, WebM and anything your browser can play. You'll get back an MP4 with the original audio and captions written directly onto the video — no separate subtitle file needed.

Yes — fully free, no signup, no watermark. We keep costs down by doing most of the work right inside your browser.

Why does it run in my browser instead of the cloud?

Three reasons: privacy (your video stays on your device), speed (no waiting in a queue behind other users), and no cost to you (we don't charge because we're not renting servers per export). The tradeoff is that export time depends on your computer — a recent laptop handles a 3-minute clip in 1 to 3 minutes.

Free AI Subtitle Generator for Video

Add animated TikTok-style subtitles to any video. AI transcribes the speech, you pick a style, your browser burns them into an MP4. The video never leaves your device. Looking for plain text instead? Use Transcribe.

1 · Upload

Drop a video to start

or browse · MP4, MOV, WebM · up to ~10 min recommended

Transcript

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Captions auto-wrap to fit the video width. Shrink the size if a line still feels too big.

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Top Middle Bottom

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Free AI Subtitle Generator for Video