Twitch Comment Custom CSS Tester is a Chrome tool developed by キィー. It serves as a Custom CSS Tester tool specifically designed for Twitch Comment Overlay. Users can preview how custom CSS will affect the appearance of their Twitch comment overlay directly in their web browser.

With this tool, users can leverage the browser's developer tool features to adjust their custom CSS in real-time while viewing the actual comment overlay. This functionality simplifies the process of fine-tuning CSS adjustments for overlays displayed through sources like OBS browser. By utilizing the web browser's developer tools, users can easily identify and rectify any custom CSS errors.