Generating an animation with AI is easy now. Making it feel right isn't: "a bit snappier" is hard to explain in a chat. Keyline is an animation editor built around your own Claude. Claude builds the animation and checks its own frames. You pause, point at what's off and leave a comment pinned to that second, and Claude fixes exactly that. Tune any move by hand with a bezier or spring curve, ask for variants side by side, pull your brand from your site's URL, and export MP4, WebM, PNG or SVG in the browser. It runs on your Claude subscription over MCP or your own API key. No credits, no markup.