What websites can detect about your installed fonts

You may wonder whether a website can read every font on your computer, or whether the fonts you have installed make you easier to identify. The short answer is that a typical website does not receive a complete list of your fonts, but it may be able to infer that some fonts are available.

Use Installed Fonts to see the fonts on your computer and preview them. This helps you understand what is installed, but it does not show exactly what a particular website has detected.

Check your installed fonts

1. Open Installed Fonts in Chrome or Edge on a computer. Those browsers provide the fullest version of the tool.
2. Review the font list and use the preview to see how a sample of your own text looks in different fonts.
3. Look for uncommon or personally distinctive fonts. These may contribute more information to a browser fingerprint than a common font that many people have.
4. Compare the list with the fonts you expect to have installed. The tool shows what the browser can access through its font listing feature, not what a website has already learned about you.

Other browsers may show a reduced version of Installed Fonts or none at all. That does not mean the browser has no fonts, or that websites cannot use fonts to render text.

What a website can learn from fonts

A website may infer whether certain fonts are available

A page can ask the browser to display text in a named font. If that font is not installed, the browser uses a fallback font instead. By comparing the width or appearance of the text, a page can sometimes infer whether a particular font is available. This is usually a check against a selection of known fonts, not a direct readout of every font on your device.

That information can contribute to a browser fingerprint: a set of details that may help distinguish one browser from others. A font list alone does not identify you by name, and many devices share the same fonts. The risk comes from combining font clues with other browser and device details.

A website does not normally get a complete font inventory

Ordinary web pages do not automatically receive a full list of your installed fonts. Some browsers support a feature called the Local Font Access API, which can provide information about local fonts after the browser grants permission. Availability and permission behavior vary by browser. If a site asks for access to local fonts, you can deny it unless the site has a clear reason to use that feature.

A website can use fonts it provides itself

Pages can download web fonts from their own servers and use them to display text. That does not tell the site that the same font was already installed on your computer. It also means that a page can look different from the fonts shown in your local font list.

What the results mean

The tool lists many fonts

Your computer has many fonts available to the browser. That can give a site more fonts to test for, but the list does not mean every site can simply read them all. If you do not need a font, you can check where it came from before deciding whether to keep it. Removing system fonts can affect how your computer and apps display text.

A font you expected is missing

The browser may not be able to list that font, or the font may not be installed for your account or system. On Windows 11, check Settings › Personalization › Fonts. On a Mac, open Applications › Font Book. A browser restart may be needed after installing a font.

A website shows text in an unexpected font

The page may be using a web font, a different font from its CSS list, or a fallback because the preferred font failed to load. This is a display choice, not proof that the site has read your whole font collection.

How to limit font information shared with websites

1. Deny local font permission when you do not need it. If your browser asks whether a site can access local fonts, choose Block. To review the choice later, open the site controls beside the address bar and check its permissions. The exact label and location depend on the browser.
2. Use a separate browser profile for sensitive browsing. Profiles keep browsing data and permissions apart. They do not hide every font clue, but they can prevent one site's permissions and stored data from carrying into another profile.
3. Keep your browser current. Browser makers update privacy protections and permission controls over time. Install updates through the browser's own settings, then restart it.
4. Review fonts before removing them. On Windows 11, use Settings › Personalization › Fonts to inspect installed fonts. On macOS, use Applications › Font Book. Avoid removing fonts your operating system or apps rely on just to reduce fingerprinting.
5. Remember that privacy modes have limits. Private browsing mainly limits what is saved on your device after a session. It does not guarantee that a website cannot infer available fonts while the page is open.

Why font checks are not the same in every browser

Browsers differ in which font APIs they support and how they restrict access. Operating systems also include different default fonts, and installed apps may add more. A result from one computer or browser therefore cannot be treated as a universal list of what websites can detect.

Installed Fonts runs in your browser. The fonts and preview text you use in the tool stay on your device.