fi is a free Chrome add-on developed by Justineo that provides users with a quick and easy way to analyze the font-family usage in a webpage. With fi, users can learn about the different font families used in a webpage and understand their usage patterns.

One of the key features of fi is its ability to ignore texts inside certain elements such as script, noscript, style, iframe, and option. This ensures that only relevant font-family usage is taken into account, providing users with accurate results. Additionally, fi also excludes invisible elements with properties like opacity: 0, display: none, and visibility: hidden.

The results generated by fi are sorted based on the number of characters each font-family applies to. This means that the most used font-family will be displayed at the top of the result list, making it easy for users to identify the predominant font choices on a webpage.

If you're looking to gain insights into font-family usage on webpages, fi is a valuable tool that can help you analyze and understand the font choices made by developers.