Can’t Open a WOFF Font? 6 Fixes

You have a WOFF or WOFF2 font, and it will not open. Maybe Windows says it cannot open the file. Maybe your Mac shows a blank icon. Maybe a viewer says it is not a font. This guide walks you through six fixes, starting with the most common one. Most people are sorted by fix number one or two.

First, what kind of “will not open” is it?

Different messages point to different problems. Find yours in this table, then jump to the fix.

What you see	Likely cause	Go to
“How do you want to open this file?”	Your system has no WOFF app	Fix 1
Font Book or Font Viewer does nothing	Desktop font tools do not read WOFF	Fix 1
“Not a valid font file” when installing	You tried to install WOFF directly	Fix 2
A viewer says it is not a font	The file is fake or damaged	Fix 3 and 4
Font opens but shows boxes	Missing characters	Fix 5
Nothing happens in the browser viewer	Old browser or connection issue	Fix 6

Fix 1: Use a tool that can read web fonts

This is the answer for most people. WOFF and WOFF2 are web font formats. Windows Font Viewer and Mac Font Book only open desktop fonts like TTF and OTF. Double-clicking a WOFF file will never work well, and it is not your fault.

Browsers can read WOFF, so use a browser-based viewer:

1. Go to openwofffile.com.
2. Drop the file on the pink box.
3. The font preview, details and glyphs appear.

Your file stays on your device. For a step-by-step guide on your system, see how to open WOFF files on Windows, how to open WOFF fonts on a Mac or how to open a WOFF2 file on any device.

Fix 2: Convert before you install

If the problem is installing, not viewing, you need a TTF or OTF file. Windows and macOS do not install WOFF or WOFF2 directly. Trying to do so gives errors like “not a valid font file”.

1. Open the font in the viewer.
2. Click “Convert & download”.
3. Install the TTF or OTF that downloads.

On Windows, right-click the new file and choose Install. On Mac, double-click it and click Install in Font Book. For the full walkthrough, read how to install a WOFF font on Windows.

Fix 3: Check that it is really a font

This one catches a lot of people. When you save a font from a website, the server sometimes sends back an error page instead. Your browser saves that page with the font’s file name. It looks like a font, but it is a small web page.

Here is how to check:

1. Right-click the file and open it with Notepad (Windows) or TextEdit (Mac).
2. Look at the first few characters.

First characters	What the file is
wOFF	A real WOFF font
wOF2	A real WOFF2 font
<!DOCTYPE or <html	A web page, not a font
{ or [	A JSON file, not a font
Mostly blank or zeros	Damaged or empty file

If it is not a font, go back to the source and save it again. In the browser’s developer tools, open the font from the Network tab in a new tab, then save it from there.

Fix 4: Download it again

A download that stopped halfway gives you a broken file. The viewer may refuse it, or show part of the font and then fail.

Signs of a broken download:

• The file size is tiny, like a few bytes or a couple of KB for a normal font.
• The file size is different from the one shown on the source site.
• The viewer says the file appears to be truncated or damaged.

Delete the file and download it again. If it keeps failing from one source, try another source for the same font. Use the font name from the viewer, or read how to find the font name inside a WOFF2 file to identify it.

Fix 5: The font opens but letters are missing

Sometimes the font opens fine, but when you type, some letters show as boxes. That means the font does not include those characters. With web fonts, this is very common.

Websites often split fonts by language to save data. A file saved from an English site may hold Latin letters only. Some sites cut fonts down even further, to just the letters they use.

Check the Glyphs grid in the viewer to see exactly what is included. If you need more, find the full font by its name. Our guide on why WOFF fonts show boxes goes into this in detail.

Fix 6: Update your browser or reload

If the viewer itself does nothing, the issue is usually the browser.

• Update your browser. The viewer uses modern browser features, especially for converting fonts. Current versions of Chrome, Edge, Firefox and Safari all work.
• Reload the page. A WOFF2 file needs a small reader that loads the first time. If your connection dropped at that moment, reload and try again.
• Try another browser. If one browser has extensions that block scripts, another may work.
• Check the file size. The viewer opens files up to 20 MB. Normal web fonts are far smaller, but full Chinese or Japanese fonts can be large.

Special cases

The font is an icon font

Icon fonts hold pictures instead of letters. When you type normal text, you see boxes. That is expected. Scroll down to the Glyphs grid to see the icons. Read how to view icons in a WOFF file for more.

The font is installed but the app does not show it

This is not an opening problem, but it feels like one. Close the app completely and open it again. Search for the font by its real family name, not the file name.

The font opens in FontForge with warnings

Font editors are strict. Web fonts are often trimmed, so editors warn about missing parts. You can usually ignore minor warnings. If you plan to edit the font, see how to edit a WOFF file.

The file has no extension

If the file has no .woff or .woff2 ending, your system will not know what it is. Check the first four characters as shown in Fix 3. Then rename the file with the right extension.

You are on a phone

Phones have no built-in font tools. Open the viewer in Chrome on Android or Safari on iPhone, tap the pink box and pick the file from Files or Downloads.

How to avoid the problem next time

A few habits save you from broken font files in the future:

• Get fonts from the source. The maker’s website, Google Fonts or a trusted font shop give you complete files.
• Keep the original. If you convert a font, keep the WOFF too, in case you need it again.
• Name files clearly. Include the family and weight, like inter-700.woff2, so you never mix them up.
• Check new fonts right away. Drop every new font into the viewer once, so you know it works before you need it.

Still stuck?

Run through this short checklist:

1. Is the file really a font? Check the first four characters.
2. Is it complete? Compare the size with the source.
3. Are you using a tool that reads web fonts?
4. Are you trying to install a WOFF directly? Convert first.
5. Is your browser up to date?

If all five check out and it still fails, the font file itself is probably damaged at the source. Try getting it from somewhere else.

Common questions

Why does Windows say it cannot open WOFF files?

Because Windows has no built-in app for web fonts. That is normal. Use a browser-based viewer.

Can a WOFF file be a virus?

A real WOFF file is font data, not a program. Browsers check web fonts carefully before using them. Still, only install fonts from sources you trust.

Can I open a WOFF font without the internet?

Yes, once the viewer page has loaded. WOFF, TTF and OTF files open offline. For WOFF2, open one file while you are online so the reader loads.

Does renaming a .woff file to .ttf work?

No. The data inside is still compressed WOFF. You need to convert it properly. See how to convert WOFF to TTF.

What if it is a WOFF2 file that will not convert?

Make sure the page has finished loading its WOFF2 reader, then try again. If it still fails, the file may be damaged. See how to convert WOFF2 to TTF.

Summary

Most WOFF fonts that “will not open” are fine. Your system just cannot read web fonts. Open the file in a browser-based WOFF viewer, and convert it to TTF if you want to install it. If the viewer rejects it, check that it is a real font, download it again, and make sure your browser is up to date.