Validate Fonts With Font Book

Validate before or after installation

Font Book can automatically validate fonts both before and after installing them.

Fonts seem like innocuous files, and most times, they are. However, like any computer file, fonts can become damaged or corrupt. When that happens, they can cause problems with documents or applications. Use Font Book on your Mac to validate installed fonts to ensure that the files are safe to use.

Information is this article applies to Font Book in the following operating systems: macOS Catalina (10.15) to Mac OS X Panther (10.3).

If a font doesn't display correctly or at all in a document, the font file may be damaged. If a document won't open, it's possible one of the fonts used in the document is the problem. Using Font Book, you can test fonts for problems and – if needed – remove them.

Also, you can (and should) validate fonts before you install them to head off future problems. Validating fonts at installation can't prevent the files from becoming damaged later, but it prevents you from installing problem files.

Font Book is included with Mac OS X 10.3 and later. You can find Font Book in the Applications folder. You can also launch Font Book by clicking the Go menu in the Finder menu bar, selecting Applications, and then double-clicking the Font Book application.

How to Validate Installed Fonts With Font Book

If you are having a problem with a font, you can check it in Font Book. You can also opt to verify all fonts on your Mac occasionally to err on the side of caution. Here's how to validate installed fonts in Font Book:

  1. Open Font Book by clicking it in the Applications folder or by accessing it from the Go menu.

    Opening Font Book from the Finder Go menu
  2. Select the font or fonts you want to validate by clicking on the font name or names in Font Book. You may have to scroll down to find the fonts you are after.

    Selection of fonts in Font Book on a Mac
  3. Select File in the Font Book menu bar and choose Validate Font from the drop-down menu.

    File menu in Font Book on a Mac
  4. Evaluate the results in the Font Validation window. Hopefully, you'll see all green circles with check marks in them next to the font names, which indicates the fonts are safe to use.

    If you see a problem font indicated by a red circle with an X in it, select the check box next to the font name and click Remove Checked to delete it.

    Font Validation screen showing a damaged font

You are prompted by your Mac to enter your password before it removes the damaged font.

If you have a large number of fonts installed, you can validate them all at once, rather than selecting individual fonts or font families. Click Edit on the Font Book menu bar and choose Select All. In the File menu, select Validate Fonts, and Font Book validates all the installed fonts.

Removing Duplicate Fonts

If you validate all your fonts, there's a good chance you may find out you have duplicate fonts. A banner at the bottom of the Font Book screen notifies you if you have duplicates.

Font Book showing duplicate font banner

Click Resolve Automatically to remove duplicates all at once without a review. A more cautious approach is to click Remove Manually to find out more about the duplicate fonts on your Mac.

Each font with a duplicate is displayed, one at a time. You are shown samples of both fonts, and the active copy is identified. You can choose to resolve the duplicate, which moves the inactive copy to the trash, or you can leave everything as is.

Duplicate font screen in Font Book on a Mac

If you do plan to remove duplicate fonts, make sure you have a backup of your Mac's data before proceeding.

How to Validate Uninstalled Fonts With Font Book

If you have collections of fonts on your Mac that you haven't installed yet, you can wait until you install them to validate them, or you can check them in advance and toss any fonts that Font Book labels as possible problems. Font Book isn't foolproof, but chances are if it says a font is safe to use (or that it has problems), the information is correct. It's better to pass on a font than risk problems down the road.

To validate a font file before installing it:

  1. With Font Book open, click File in the menu bar and select Validate File.

    Font Book showing Validate File option
  2. Locate the font on your computer. Click once on the font's name to select it and then click the Open button. (Select multiple fonts by holding down the Shift key and clicking on the fonts you want to validate.)

    Screen showing location of a downloaded font on a Mac
  3. The font validation window displays whether the chosen font is safe to install or has potential problems. If the font is OK, place a check mark in front of its name and click Install Checked to install the font. If the font has problems, it is best not to install it.

    Font Validation screen on a Mac