Caption Generator, Auto Captions Free

Drop your video or audio file here

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Supports video and audio files up to 2048MB

How to add captions to a video

1 Drop your video
Click or drag a video or audio file onto the drop area. The file is read into the browser tab and never uploaded anywhere.
2 Check the words and pick a style
Whisper transcribes the speech on your device. Fix any wrong words in the transcript, then pick a caption preset or set the font, color, size, background and position. The preview over the video shows exactly what the burn-in will look like.
3 Burn in and download
Press Burn in and download MP4 to get the video with captions baked in, or download an SRT or VTT file to upload alongside the video instead.

What the caption generator does, and its limits

This tool generates captions for any video, entirely in your browser tab. The file you drop on the page stays on your device. Speech recognition runs locally against a Whisper model, captions render in a live preview, and the final output, whether burned into the MP4 or exported as an SRT or VTT file, comes off your own machine. No upload, no transcoding queue, no account to make.

Pick a styling preset or build your own (font, color, size, position, background pill, karaoke highlight), fix any words Whisper got wrong in the transcript, then export. The default is a burn-in, where the captions are baked into the video frames so they show up everywhere, including apps that ignore caption files.

Running it in the browser has three practical effects. Privacy-sensitive material such as medical clips, legal recordings or anything under NDA stays on your device. There is no watermark, export cap or signup gate in front of the download. And there is no queue: a 30-minute lecture takes as long as your laptop needs.

The limits: the speech model on this page understands English only. Files can be up to 2 GB. Burning captions in is heavy work, so on a phone keep it to clips under about five minutes, or download the SRT and burn it in on a desktop.

Adding a subtitle file you already have

If you already have an SRT, ASS or VTT file, for example a translation or subtitles from a professional captioner, there is nothing to generate. The subtitle file tool burns an existing file into the video, adds it as a soft track viewers can switch off, or converts between formats.

On this page you can still get close to your own wording. After Whisper produces the first pass, you can rewrite every line, split or merge segments, or delete them, so a script or translation can replace the spoken words one segment at a time. It cannot start from a silent or music-only video, because there is no speech to split into segments, and timecodes cannot be typed in by hand.

When this fits

TikTok and Reels

Burn captions directly into 9:16 video so they show up even when viewers watch with sound off. Choose top, middle, or bottom placement and check the live preview against where each app draws its own buttons.

YouTube videos and Shorts

Export an SRT to upload alongside your video for closed captions, or burn them in for Shorts where the platform deprioritizes opt-in captions.

Course content and tutorials

Auto-generated captions help comprehension and watch time. Edit the transcript inline to fix technical terms and acronyms Whisper does not recognize.

Accessibility

Closed captions are part of WCAG 2.1 compliance for video content. Generate them locally, then fix wrong words and add speaker labels in the inline editor.

Frequently asked questions

How do I add captions to a video?

Drop the video on this page. Whisper transcribes the audio in your browser and turns it into timed captions. Fix any wrong words, choose a style, then press Burn in and download MP4. If you would rather upload captions to YouTube or Vimeo as a separate file, download the SRT instead.

Is my video uploaded anywhere?

No. The file you drop on the page is read by the browser tab and stays there. Speech recognition runs locally against a Whisper model that downloads once and caches in your browser. Watch the Network tab in DevTools while you generate captions: you will not see a request carrying your video. The site does send anonymous usage events and error reports, but your media is never in them.

How accurate are the captions?

Accuracy depends on audio quality. Clean English speech typically lands around 90 to 95 percent on the desktop model, a little lower on the smaller phone model. Heavily accented speech, technical jargon, or low-quality audio drops the accuracy. The transcript editor is built for fixing these cases quickly.

What languages are supported?

English only, today. This page loads the English Whisper models (base.en on desktop, tiny.en on phones), so non-English audio will come out wrong. If you need another language, Orator at /text-based-video-editor has a multilingual option on desktop.

Can I burn the captions into the video itself?

Yes. The main export burns the captions directly into the MP4 video frames, which means they show up on every platform and every device, even ones that do not support closed captions.

Can I use my own subtitle file instead of generating one?

Yes, with the subtitle file tool, which burns an existing SRT, ASS or VTT file into a video. On this page you can also overwrite every generated line with your own text before you export.

Is there a limit on how long the video can be?

No length cap on the captioning itself, but very long videos depend on your device having enough memory to hold the audio and run Whisper. On laptops you can comfortably handle hour-long content. On phones the page warns you past five minutes and suggests downloading the SRT instead of burning in.

Will there be a watermark on the exported video?

No. The burn-in export contains only your video and the captions you styled. No VidStudio logo, no watermark, no signup wall in front of the download.

Auto Caption Generator

Drop your video or audio file here

How to add captions to a video

1 Drop your video

2 Check the words and pick a style

3 Burn in and download