WOFF file format: what it is and how to use it

WOFF is the Web Open Font Format: fonts compressed and wrapped for @font-face delivery, the format that made custom web typography practical. Learn when to use it and what to choose instead.

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What is a WOFF file?

A .woff file is a font in the Web Open Font Format, the W3C standard that wraps a TTF or OTF for web delivery: zlib-compressed font tables plus metadata, designed for @font-face and nothing else. It solved the font problem of the 2009 web, bandwidth and licensing, and made custom typography practical. Today it is the universal fallback behind its successor WOFF2.

When should you use WOFF?

  • Fallback webfonts: the format every browser since IE9 understands.
  • Compatibility-critical delivery: when the audience might run old software.
  • Licensed web font files: many foundries still ship it alongside WOFF2.

When is another format a better fit?

For primary delivery use WOFF2, ~30% smaller and universally supported now. For desktop installs TTF or OTF. WOFF's role today is the safety net, not the front line.

The short version: WOFF is the web font fallback: serve WOFF2 first, WOFF for the browsers that missed the memo.

How to open a WOFF file

On Windows

Double-click the file, or open it with Windows Font Viewer.

On macOS

macOS Font Book opens WOFF files on macOS.

In your browser

Open WOFF files right in a browser tab or with the dexrr viewer. No install, no upload.

Also opens in

  • Any web browser
  • FontForge
  • macOS Font Book
  • Windows Font Viewer

View or convert WOFF files

A quick preview or a new format. No install, no upload.

View WOFF files Preview and inspect WOFF files Convert to WOFF Turn files into WOFF WOFF to WOFF2 Web Open Font Format 2 WOFF to TTF TrueType font WOFF to OTF OpenType font

WOFF technical details

Full name
Web Open Font Format
Extensions
.woff
MIME type
font/woff
Magic bytes
77 4F 46 46 (wOFF)
Compression
Lossless
Developer
W3C
Specification
www.w3.org

WOFF questions, answered

How do I open a .woff file?

It is a web format, not a desktop install. Browsers load it via @font-face; font tools can unwrap it back to ttf/otf. dexrr displays and converts woff files in your browser.

Can I convert WOFF files online?

Yes, dexrr converts woff locally in your browser: WOFF to TTF or WOFF to OTF for desktop use, or WOFF to WOFF2 for better compression.

Is WOFF better than WOFF2?

No. WOFF2 compresses ~30% better with Brotli. WOFF survives as the fallback for the oldest browsers still in the wild.

Can I install a .woff font on my computer?

Not directly, it is a web wrapper. Convert it to TTF or OTF first, then install normally.

Is the WOFF format outdated?

Superseded but not dead, it remains the standard fallback paired with WOFF2 in @font-face stacks.