This paper introduces a web-based integrated design environment named “TextAlive Online” that supports creating Kinetic Typography videos synchronized with songs available online. It is the hybrid of a content authoring tool and a live programming environment. Through its development, we investigate the interaction design that most benefits from the interactive user interfaces used by designers and programmers, as well as the collaborative nature of the open-source culture on the web. This system is accessible at textalive.jp and the interactive “live” version of this paper is available at textalive.jp/paper.