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TTF / OTF / WOFF supported
What is Font Subsetter Tool?
Web fonts enhance design quality but, especially for CJK languages like Japanese, can contain thousands of glyphs, resulting in files of several megabytes. Font subsetting extracts only the characters you actually use, dramatically reducing file size.
This tool uses opentype.js (MIT License) for high-precision subsetting entirely in your browser—no server upload required.
Key Features
- ✂️ Extract only needed characters to reduce file size
- 📂 TTF / OTF / WOFF input support
- 📋 Preset character sets (ASCII, Latin Extended)
- 👁️ Real-time preview with subset font
- 📊 Reduction rate and glyph count visualization
- 🔒 All processing in your browser
How to Subset a Font
Step 1: Upload Font
Upload a TTF, OTF, or WOFF font file.
Step 2: Enter Characters
Choose a preset or type the characters you need directly.
Step 3: Run Subset
Click "Run Subset" to process, preview, and download.
What is Font Subsetting?
Font subsetting removes unused glyphs from a font file, reducing its size. For CJK fonts, this can achieve 90%+ reduction.
Font Format Comparison
| Format | Compression | Browser Support | Recommended Use |
|---|---|---|---|
| TTF | None | All Browsers | Desktop / Fallback |
| OTF | None | All Browsers | Desktop / Print |
| WOFF | ZLIB | All Browsers | Web (Legacy) |
| WOFF2 | Brotli | Modern Browsers | Web (Recommended) |
Frequently Asked Questions
- Q. How much can subsetting reduce file size?
- A. For CJK fonts, 90%+ reduction is common. For ASCII-only, 95%+ is possible.
- Q. What are the downsides of subsetting?
- A. Characters not included will fall back to system fonts. Be careful with dynamic content.
- Q. Is any data sent to a server?
- A. No. opentype.js processes everything in your browser.
- Q. Does this output WOFF2?
- A. This tool outputs TTF. For WOFF2 conversion, use a separate tool.
- Q. Any licensing concerns?
- A. opentype.js uses the MIT License. Check your font's own license terms separately.
Font Subsetting Use Cases
Web Performance
Subset CJK web fonts to drastically improve LCP/FCP/CWV scores.
Mobile Apps
Minimize bundled font size to reduce app download size.
HTML Emails
Optimize embedded fonts with limited character sets.
Games & Digital
Bundle only needed characters for faster load times.
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