Helix Font Fallback is a Chrome add-on developed by Adobe Inc. that helps prevent Cumulative Layout Shift (CLS) by computing fallback fonts for all the fonts loaded on a webpage. CLS is one of the Core Web Vitals that measures the visual stability of a webpage. By using fallback fonts, the add-on ensures that the browser can display the page nicely while the custom font is being loaded, reducing the chances of unexpected layout shifts.

One of the key features of Helix Font Fallback is its ability to generate CSS code that can be easily copied and pasted into the existing website's CSS. This makes it convenient for web developers to implement the fallback fonts without much effort. Additionally, the add-on allows users to preview the fallback fonts directly on the current page, enabling them to see how the fonts will look before making any changes.

With its focus on preventing CLS and providing a simple way to implement fallback fonts, Helix Font Fallback is a valuable tool for web developers and designers who want to improve the user experience of their websites.