THE FILE FIELD GUIDE

.woff

Web Open Font

Fonts

WOFF is a webfont wrapper, used through CSS @font-face rather than ordinary desktop installation. Check URL, CORS, family/weight matching and glyph coverage when rendering fails. Verify that the license permits web embedding.

What it is used for: Compressed fonts referenced by web pages
What the file contains: Binary data

All sections, questions and sources

Content reviewed：2026-10-13 · Editor：Kai

Opening steps

Choose your environment or purpose to see its steps.

Identify the web font

Web use differs from desktop installation.

Check provenance and webfont licensing.
Compare CSS family, weight, style and files.
Check required glyphs on a test page.

Load through CSS

Placing the file alone does not apply it.

Point @font-face src to the actual file.
Match element family and weight with the declaration.
Render over HTTP and inspect the font actually used.

Diagnose loading failures

Distinguish fetch failures from missing glyphs.

Inspect the network response.
Inspect CORS/server settings for cross-origin files.
If loaded, inspect fallback and glyph coverage.

Menu labels and support vary by app, OS and version. Preserve the original before making changes.

Troubleshooting by symptom

Fallback font: check family/weight/style matching and network errors.
Only Latin changes: inspect Japanese glyph coverage and subsets.
Cross-domain failure: inspect the font host’s CORS policy and URL.
Unexpected bold: inspect weight mapping and synthetic bold.
Stale font: inspect resource URL and cache.
Same-name font differs: inspect local references and rendered font.

Licensed source font → WOFF / WOFF2

Prefer the vendor’s webfont package and confirm conversion permission/glyph coverage.
If authorized, convert a copy and compare appearance, missing glyphs and weights in a browser.
Convert an authorized source and test glyph and weight coverage.

Renaming WOFF to TTF does not make a desktop font; conversion does not change license rights.

Loaded versus rendered font

Compare element CSS with rendered fonts; a successful request does not prove every glyph uses the font.

Example: when only Latin text changes, inspect Japanese coverage and rendered fallback.

Source for these steps：W3C · WOFF File Format 1.0 / W3C · CSS Fonts Module Level 3

Preserve deployment configuration

Retain CSS and licensing and recheck CORS, weights and subsets after deployment.

Source for these steps：W3C · WOFF File Format 1.0 / W3C · CSS Fonts Module Level 3

Related-format differences

Related-format differences
Format / method	Role	What to verify
WOFF	Webfont container	CSS/license
WOFF2	Different compression	Requires conversion
OTF / TTF	Font source	Web-use rights

Handling and security

Use trusted font vendors and review external hosting and license conditions.

Questions and answers

Should I install it by double-clicking?

WOFF is for the web; obtain a licensed desktop original.

Does uploading it change the site font?

CSS definition and use are required.

Does it contain all Japanese glyphs?

Coverage depends on the typeface and subset.

Can a loaded font still be partly unused?

Missing glyphs use fallback fonts; compare required characters with coverage.

Does web use permission allow conversion?

Conversion, redistribution and subsetting depend on the license.

Format facts: name, steward and MIME type

Formal name: Web Open Font Format 1.0
Steward / specification: W3C
MIME type: font/woff

Primary and official sources

StandardWOFF File Format 1.0
Defines the webfont wrapper and distinction from desktop installation.
W3C · Link checked：2026-10-13
StandardCSS Fonts Module Level 3
Defines @font-face and font loading requirements.
W3C · Link checked：2026-10-13