The Subtitle overlay tool is a free Storrito tool that burns animated, per-word styled subtitles onto a video — entirely in your browser. Drop in a clip and a transcript, pick a preset, tweak typography and animation, and download a captioned MP4. No upload, no signup, no watermark.
You can find it at storrito.com/tools/subtitle-overlay.
What you can do with it
- Drop a video: MP4, MOV or WebM. The video stays on your device.
- Add a transcript: if you transcribed the clip with the Storrito Subtitle generator, the words load automatically. Otherwise drop in any Whisper-shape per-word JSON.
- Pick a preset: starting points for typography, color, position and animation.
- Fine-tune: adjust font, size, color, stroke, position and per-word animation. The live preview updates frame-for-frame against the final render.
- Render and download: get an MP4 with captions burned in. Render time is roughly real-time on a modern laptop with hardware video encoding.
How it works under the hood
Audio passthrough, frame composition and re-encoding all happen in your browser via the WebCodecs API. The live preview and the final render call the same draw function, so what you see is what you ship — there's no surprise difference between the preview and the exported MP4.
When it works best
- You have a per-word transcript (use the Subtitle generator first).
- The clip is short — render time scales with length. Trim long videos first.
- The video uses common codecs (H.264, H.265 or VP9). MP4s from a phone or a screen recorder almost always work. Some unusual codecs decode for playback but can't be re-encoded in the browser.
- One speaker, so the captions don't overlap meaning.
Where it fits
The tool is free and standalone. No Storrito account is required. If you'd like to schedule the captioned video as a Story or Reel, the main Storrito product handles that.
If you have feedback or run into trouble, reach out to support.