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.WOFF file extension

To open .WOFF files on Windows, for web use: put the .woff file in your project folder and reference it from CSS with @font-face (point src: url('yourfont.woff') format('woff')).

To open a .woff file, the most common approach is to use it as a web font in a browser via CSS (e.g., with @font-face). If you just want to view what it contains, use a font viewer/editor that can preview WOFF or inspect it through your browser’s developer tools.

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Last updated: June 12, 2026

Open on your device

Choose your operating system for a dedicated step-by-step opening guide.

How to open .WOFF files

Use these platform-specific instructions to open .WOFF files safely.

Windows

  1. For web use: put the .woff file in your project folder and reference it from CSS with @font-face (point src: url('yourfont.woff') format('woff')).
  2. Open the HTML page in a modern browser to confirm the font loads and renders.
  3. For inspection: use your browser’s Developer Tools (Network tab) to verify the .woff file is served and the correct type is applied.
Full Windows guide

Mac

  1. For web use: add the .woff file to your site/project and reference it from CSS using @font-face (src: url('yourfont.woff') format('woff')).
  2. Open the page in a modern browser and verify the font is applied.
  3. If you need to debug loading, use browser Developer Tools to check the font request and response headers.
Full Mac guide

Linux

  1. For web use: place the .woff in your project and reference it from CSS using @font-face with format('woff').
  2. Load your page in a modern browser and confirm the font renders.
  3. Use browser Developer Tools to troubleshoot if the font fails to download or apply.
Full Linux guide

iOS

  1. Most iOS use cases involve .woff being loaded by a web page in the browser; to view it directly, open a page that references the font rather than trying to install it as a system font.
Full iOS guide

Android

  1. Most Android use cases involve .woff being loaded by a web page in the browser; for direct viewing, test it by referencing it in a simple web page and opening the page in a browser.
Full Android guide

Security notes

  • WOFF files are font resources, not scripts, but they are still binary files parsed by browsers and font libraries; malformed fonts can trigger parser vulnerabilities in consumers (browsers, rendering engines, or font tooling). Treat untrusted web font files as potentially risky inputs.
  • In web deployments, only load fonts you trust and serve them from controlled origins; review third-party font sources because they run through the browser’s font parsing and rendering pipeline.
  • Be careful with server configuration: serving the correct media type (font/woff) helps browsers handle the resource as a font; incorrect handling can cause failures or unexpected behavior.

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Can't open this file?

These are the most common causes and fixes when .WOFF files fail to open.

Common reasons

  • Font doesn’t load on the website (wrong MIME type or server configuration)
  • CSS @font-face reference is wrong (path/format mismatch)
  • Confusing .woff with .woff2

Fix steps

  1. Configure your web server to serve .woff with the standardized media type font/woff (per the IETF/IANA registration).
  2. Re-test in the browser and confirm in Developer Tools that the response Content-Type is font/woff.

OS-specific troubleshooting

What is a .WOFF file?

WOFF (Web Open Font Format) is a compressed font file format designed primarily for use on the Web. It is a container for font data (commonly based on TrueType/OpenType outlines) packaged for efficient web delivery, as specified by the W3C WOFF 1.0 Recommendation. WOFF 2.0 is a newer, separate format with its own specification; .woff refers to WOFF 1.x, while .woff2 is used for WOFF 2.0.

Background

WOFF was standardized by the W3C as a web-optimized way to distribute fonts, so browsers can download and use fonts on demand without requiring users to install them locally. In practice, .woff files are most often found inside website assets (for example, in a site’s /fonts/ folder) and referenced from CSS using @font-face.

From a developer perspective, WOFF is less about “opening” a file in an app and more about serving it correctly over HTTP and referencing it properly in CSS so browsers can use it. Correct media type (MIME type) configuration can matter, and the standardized media type for WOFF is under the IETF/IANA “font” top-level type.

If you have a standalone .woff file, you can still inspect it: font tools may preview it, and web developers often verify it by loading it in a simple HTML page and checking in browser dev tools that the font downloads successfully and is applied to text.

Common MIME types: font/woff

Further reading

Authoritative resources for more details on the .WOFF format.

Common .WOFF issues

Font doesn’t load on the website (wrong MIME type or server configuration)

Browsers expect web fonts to be served with an appropriate media type. If the server sends an incorrect type (or a deprecated one), the font may fail to load or be blocked by policies in some configurations.

  1. Configure your web server to serve .woff with the standardized media type font/woff (per the IETF/IANA registration).
  2. Re-test in the browser and confirm in Developer Tools that the response Content-Type is font/woff.

CSS @font-face reference is wrong (path/format mismatch)

A common practical issue is a broken URL path to the .woff file or an incorrect format() hint in @font-face, causing the browser to skip the source.

  1. Verify the URL in src: url(...) points to the actual .woff location and that the file is accessible (no 404 in Network tab).
  2. Use format('woff') for .woff sources and ensure the @font-face family name matches what you use in font-family.

Confusing .woff with .woff2

.woff and .woff2 are different formats with different specifications. Serving only one when the client expects the other can lead to missing fonts on some setups (especially when older assets or build pipelines are involved).

  1. Confirm whether you have .woff (WOFF 1.x) or .woff2 (WOFF 2.0) files; don’t rename extensions to “convert.”
  2. Provide the appropriate sources in @font-face (often listing both .woff2 and .woff, each with the correct format hint) if you need broader compatibility.

FAQ

What is a .woff file used for?

It’s a web font file used by websites so browsers can download and render custom fonts via CSS (commonly using @font-face).

Is .woff the same as .woff2?

No. WOFF 1.x uses the .woff extension and is specified separately from WOFF 2.0, which uses .woff2.

What MIME type should my server use for .woff?

The standardized media type is font/woff, defined under the IETF “font” top-level media type and listed in IANA’s media type registry.

Can I install a .woff file like a normal desktop font?

WOFF is designed primarily for web use. Some tools can preview or convert fonts, but for general desktop installation workflows, traditional font formats are more commonly used.

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