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Animated auto captions for YouTube Shorts, Reels and TikTok

The bold, bouncing captions you see on Shorts, Reels and TikTok are usually made in a dedicated caption app. AutoSub does the same job in your browser: it transcribes the speech, lets you fix it, then burns animated captions into an MP4 that's ready to post.

Open AutoSub free30 free minutes when you sign up. Works best in Chrome or Edge on desktop.

Caption styles you can use

Each style is a starting point you can preview on your own footage before exporting:

• Shorts / Reels: large, high-contrast text designed for vertical feeds.
• Pop: words animate in as they're spoken.
• One word: a single word at a time, for punchy, fast-cut edits.
• Emoji: adds emoji alongside the captions for a playful look.
• Clean, Broadcast, Lower band and Minimal: calmer looks for interviews, tutorials and talking-head videos.

Any style can use the word-by-word highlight, which lights up each word as it's spoken, karaoke-style. Because the transcript includes word-level timing, the highlight follows the speaker rather than sweeping at a fixed speed.

Step by step

1. Open AutoSub. Go to autosub.isroot.in in Chrome or Edge. There is nothing to download, though you can install it as an app from the address bar if you'll use it often.
2. Pick the spoken language. Choose the language people speak in the recording, or leave it on auto-detect. Picking it explicitly helps with short clips and heavy accents.
3. Drop in your file. Drag your vertical video onto the page (or click to browse). AutoSub decodes it in the browser and uploads only compressed, speech-only audio for transcription. Sign in when asked; new accounts get 30 free minutes.
4. Tighten the captions. Short-form captions work best in small chunks. Split long cues, fix any misheard words and check that each caption appears exactly when it's spoken. Click a line to jump the video to that spot.
5. Pick a style and export the MP4. Open the burn-in panel and try styles such as Shorts / Reels, Pop, One word or Emoji. Turn on the word-by-word highlight for a karaoke effect, scrub through to check it, then export. The MP4 is rendered on your device and ready to upload.

Tips for short-form captions

• Short chunks beat full sentences. Three to six words per caption is easier to read at scrolling speed.
• Mind the platform overlays. Like buttons, captions and usernames sit on the right edge and bottom of the screen in most apps. Preview your export on your phone before posting.
• Fix the hook. The first two seconds matter most. Make sure the opening line is spelled correctly and timed precisely.
• Batch your week. Drop several clips at once and work through them in one sitting.

How AutoSub compares

Dedicated caption apps are polished, but most are priced on a monthly subscription with a modest minute allowance. Approximate public list prices at the time of writing:

Competitor prices change; check their sites for current plans. AutoSub also never uploads your video: it is rendered on your own computer, and only compressed speech audio is sent for transcription.

Frequently asked questions

Why add captions to Shorts and Reels at all?

Many people scroll with the sound off, and captions help viewers follow along whether or not the audio is on. Animated, word-by-word captions also give the eye something to track, which suits fast-paced short videos.

Can't I just use TikTok's or YouTube's built-in auto captions?

You can, but built-in captions offer limited styling, can differ between platforms, and are harder to correct in bulk. Burning captions in with AutoSub gives you one edited, consistently styled video you can post everywhere.

Is there a watermark?

Free burned-in exports include a small AutoSub watermark in the corner. Any purchase, including the one-time $7 pack of 300 minutes, removes it.

Does it support vertical 9:16 videos?

Yes. The captions are drawn onto your video at its own size and aspect ratio, so vertical, square and horizontal videos all work. Preview the style on your footage before exporting.

How does the price compare with other caption apps?

AutoSub Pro is $9.99 a month for 1,000 minutes. Approximate public list prices for comparable tools at the time of writing: Submagic from about $19 a month, VEED Basic about $18 a month for roughly 100 minutes, and Kapwing from about $16 a month. Check each vendor for current pricing.