Font Validator

All fonts are tested for quality in Foundry Platform. This is to prevent fonts with issues from being released to the live site in order to proactively reduce customer issues! We recommend utilizing these tools as quality control for your fonts and to as a way to grow your font skills. 

There are three error states:

		Red errors will prevent your fonts from being submitted. Please correct any issues and re-upload your fonts.
		Yellow warnings will not prevent your fonts from being submitted. These warnings may not apply to your fonts, so please read the details of each warning. A member of the foundry team will double check these warnings when reviewing your fonts.
		Blue approvals indicate that your font passed this check.

The font validator does not judge the style or design of your fonts. It focuses on catching technical issues. You can see all the tests run below. Companion articles outline each issue in more detail. 

One of the most important checks our validator runs is checking your font to see if it has enough characters to support customer's needs. We recommend creating fonts that meet our recommended character set. When you see the validator results, click the row or the arrow to the left of the row to expand and learn more. The missing characters will be listed separated by commas. You can see an example of the character set validation of a real font submission above. 

The font validator checks the left and right side bearings on specific glyphs in your font. This helps us confirm that spacing across your typeface is consistent.

Many new designers tend to align a letter all the way to the left side of the glyph box, leaving most of the space on the right side. While it may seem harmless, this creates several spacing problems later:

• It makes the font harder to kern and manage during design.
• It causes layout issues for customers, because text may shift unexpectedly.
• It creates subtle visual discomfort while typing, as letters don’t feel centered within their boxes.

To avoid these issues, glyphs should be roughly centered inside their glyph boxes. 
Keep in mind that perfect symmetry isn’t required, basic type design principles often call for slightly different amounts of space on each side. You can explore more about the principles of spacing in our common errors in type design series.

If you’re working with an italic or script typeface, please disregard this check. These styles interact with the glyph box differently and will almost always appear off-center compared to upright fonts.

When glyph counters have incorrect winding directions, counters which should be white will disappear and become black. Paths need to be oriented counter-clockwise, counters need to be oriented clockwise. 

You can fix this easily in your fonts by selecting all glyphs and using the "Correct Path Direction" command in Glyphs App.

Overview

This is a yellow warning. You can safely submit your fonts even if this appears, but it is still important to understand what causes it and how to fix it.

If you see this warning, it means that some of the paths in your font are overlapping. Overlaps can lead to unexpected rendering results on customer devices and may increase your file size. Cleaning these up gives you a more reliable and efficient font file.

Why this happens

When the paths that form a glyph intersect or overlap each other, the system flags it. Scripted drawing, auto-tracing, or combining contours without merging them are common causes.

How to fix it

The straightforward fix is to remove overlapping paths.

Option 1: Remove Overlap in your design file

1. Select all glyphs.
2. In Glyphs App, go to Filter > Remove Overlap. 
   This quickly resolves most issues.

Option 2: Remove Overlap at export

If you prefer to keep your working file untouched, you can remove overlaps only during export.

1. Open the Export dialog in Glyphs.
2. Enable Remove Overlap. 
   This lets you work non-destructively while ensuring your production font exports cleanly.

Option 3: Use a custom parameter

You can also automate the process:

1. Go to File > Font Info > Instances.
2. Add a Filter parameter.
3. Set its value to “Remove Overlap”.

Special case: Variable fonts

Variable fonts often need overlapping or intersecting paths to function correctly. If you are building a variable font, you can ignore this warning.