Reelsi makes short-form reels from a prompt plus your video, website, store, graphic or podcast. Watch it build in the browser, ask for changes in chat ("smaller captions", "faster after 0:17") and download in full quality. It cuts long content into clips, turns store links into product reels and listing pages into real-estate reels. A REST API and an MCP server let Claude, ChatGPT or Grok create and revise reels.