Font Loading Strategy Guide
Visually simulate and understand different CSS `font-display` values like `swap` and `block` (FOUT vs. FOIT).
About This Tool
How a browser loads your web fonts can significantly impact user experience. This tool visually demonstrates the effect of the CSS `font-display` property. You can simulate different values to understand the difference between FOUT (Flash of Unstyled Text) and FOIT (Flash of Invisible Text) and make the best choice for your site's performance and user perception.
How to Use
- Select a `font-display` strategy from the dropdown menu. 'swap' is the most common.
- Click the 'Simulate Load' button.
- The preview box will first show the fallback state (e.g., invisible or with a system font) and then transition to the web font once it 'loads'.
- Try different strategies to see how they affect the initial rendering of text.
Frequently Asked Questions (FAQs)
What is FOUT vs. FOIT?
FOIT (Flash of Invisible Text) happens with `font-display: block`, where text is hidden until the font loads. FOUT (Flash of Unstyled Text) happens with `font-display: swap`, where a fallback system font is shown first, then swapped with the web font. FOUT is generally better for user experience.
Which strategy should I use?
For most content, `font-display: swap` is the best choice. It gets text on the screen as quickly as possible, which is great for perceived performance. `optional` can be good for non-essential fonts.