Subtitle overlay

Burn animated word-by-word captions onto a video. Pick a preset, tweak typography, position and animation, and download a captioned MP4 - all in your browser.

  • Free
  • Runs in your browser
  • No watermark
  • Per-word animation
  • No signup

Render done. Auto-post the captioned reel with Storrito.

Drop the captioned MP4 into Storrito, pick the day and time, and it auto-posts as an Instagram Reel, Story, or TikTok video. Add link, poll or quiz stickers if it's a Story. Free mode included.

Try Storrito free →

How to use it

  1. Drop a video

    Click the preview area or drop an mp4/mov/webm onto the page. The video stays on your device.

  2. Add a transcript

    If you transcribed this clip in our Subtitle Generator the words load automatically. Otherwise drop a Whisper-shape JSON file or pick one with the prompt that appears.

  3. Style and render

    Pick a preset, fine-tune typography, colors, position, and animation. Hit Render & download to get an MP4 with captions burned in.

Why animated word-by-word captions outperform plain subtitles on Reels and TikTok

Static captions sit at the bottom of the screen and let the viewer read at their own pace. Animated captions, where each word lights up the moment it is spoken, behave differently. They pull the eye, they hold attention, and they read more like a thumbnail than like a transcript. That is why almost every short you scroll past on TikTok and Instagram Reels uses them.

Until recently the only way to get this look was a desktop video editor with a caption template, or a paid SaaS that uploaded your clip to a server farm and charged per minute. The Subtitle Overlay tool gives you the same finished look in your browser, with no upload and no subscription.

How the Subtitle Overlay burns captions into a video

The tool needs two inputs. A video file. And a transcript with a time for every word. Drop both onto the page, pick a preset, and the live preview updates as you change the typography, the position, the colors, or the animation. When the look is right, click Export video and the tool walks through the source one frame at a time, draws the captions onto each frame, and saves the result as a new video file with the captions baked in.

The audio is copied across untouched, which means the export sounds exactly like the source. The video resolution is preserved as well, so a 1080 by 1920 vertical clip in stays a 1080 by 1920 vertical clip out.

Where the transcript comes from in the Subtitle Overlay

There are two paths.

If you generated the transcript with our Subtitle Generator first, the words load automatically when you open the same video here. A green confirmation banner at the top reads "Auto-loaded transcript" with the word count, so you know the words are ready. No second upload needed.

If you have a transcript from somewhere else, drop the file on the page. The tool accepts the per-word transcript format that most modern transcription services produce. If the file shape is recognized, the words load and the green banner appears.

If you have no transcript yet, click the "Open Subtitle Generator" button on the prompt that appears once a video is in. The Subtitle Generator opens with the same video already loaded, so you transcribe once and come back here to style.

How to pick a Subtitle Overlay preset that fits your video

Five presets cover the most common social-video looks:

  • Minimal: a clean Montserrat sentence at the bottom, no animation. Good for explainer content where the captions are a backup, not the show.
  • Social Pop: one bold word at a time inside a yellow pill. The TikTok creator default. Pulls the most attention.
  • Karaoke: the active word fills with color while the surrounding sentence stays white. Good for music clips and vlogs.
  • Subway: tall Anton lettering with red highlights. Reads as cinematic and punchy.
  • Title Card: large Bebas Neue at the top, fade-in animation. Good for opening hooks.

Start with the preset closest to the look you want, then tweak. Font, size, color, position, animation, and shadow are all live-adjustable. The preview shows exactly what the export will look like, so what you see is what you ship.

When the in-browser Subtitle Overlay is not the right tool

Render time scales with clip length. A 30-second clip exports in about 30 seconds on a normal laptop. A 10-minute clip will work but is slow enough that you will want to leave the tab open and walk away.

If you are captioning a long-form interview, a documentary, or anything with multiple speakers who need different colors, reach for a desktop editor. The Subtitle Overlay is built for short-form content that lives or dies on its captions, which is most of what social-first teams post anyway.

Frequently asked questions

Is my video uploaded anywhere?

No. Audio passthrough, frame composition, and re-encoding all happen in your browser via the WebCodecs API. Nothing ever touches a server.

What's a 'Whisper-shape' JSON?

It's the per-word JSON format OpenAI's Whisper CLI emits, with segments containing nested word arrays. Our Subtitle Generator exports the same shape, and most modern transcription pipelines (faster-whisper, WhisperX) read it without adapter code.

How long does rendering take?

Roughly real-time on a modern laptop with hardware video encoding - a 1-minute clip renders in about a minute. Older machines or unusual resolutions can take noticeably longer; the progress bar tracks it.

Will the rendered MP4 look exactly like the preview?

Yes. Both the live preview and the burn-in render call the same draw function, frame-for-frame, so what you see is what you ship.

Can I save and reuse my custom style?

Not yet. Presets are a starting point; tweak from there. We're considering a saved-style feature - if you'd find it useful, drop us a line via the chat.

What if the rendered MP4 has no audio or fails to encode?

Some unusual codecs decode for playback but can't be re-encoded in the browser. Try a clip with H.264 video and AAC audio - those work everywhere. mp4 from a phone or screen-recorder is almost always fine.

MP4 in hand. Schedule the post.

Auto-post your captioned clip as a Reel, Story or TikTok with Storrito. Web Story editor with interactive stickers. Free mode to try it.

Try Storrito free →

Free mode included. Instagram Stories, Reels and TikTok videos.