Chitransh Gupta
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Reel Tool

Prototype

GTM and agent tools · 2026

Turns an animated HTML slide into a ready-to-post MP4, entirely in the browser.

No server, no ffmpeg, no upload. Drop in an HTML file with CSS or JS animations, external fonts and assets get inlined automatically, and it records a 1080x1920 H.264 video client-side with the WebCodecs API. A second mode composites a background image with a draggable video overlay.

Reel Tool's HTML to Reel screen, with a real Instagram carousel slide ('AI is killing tech jobs. The data disagrees.') rendered in the preview

Why it exists

Exporting an animated HTML slide to video usually means a screen recorder or a headless-browser script. After doing that by hand for a few real Instagram carousels and reels, this replaced it with a tab.

What it does

  • External stylesheets (including Google Fonts), scripts, and every CSS url() reference are fetched and inlined automatically, so an uploaded slide renders correctly with no live network access.
  • Encodes H.264 video frame by frame in the tab using the WebCodecs VideoEncoder API and mp4-muxer, no server round trip and no ffmpeg binary.
  • A second mode composites a background image with a video overlay you drag and resize directly in the preview, then exports the same way.
  • Built to replace a real workflow: a Lenny-style data carousel and a couple of Instagram reels were made by hand first, then this generalized it.

Built with

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