FubakoCompress a PDF Offline on Mac (Free, Quality Presets)
"The attachment is too big — but it's confidential, so I can't upload it to a web compressor." Here's how to resolve that classic bind entirely inside your Mac.
Why the built-in option disappoints
Preview.app does have "Reduce File Size" (a Quartz filter), but it recompresses every image with one aggressive setting — often degrading text to a smudge — and offers almost no control. The gap is real enough that single-purpose paid compressors exist just for this.
The two real reasons PDFs are heavy
- Overscaled images — photos and scans usually carry far more resolution than their printed size on the page needs
- Fully embedded fonts — Office exports often embed an entire font (megabytes) even when only a few hundred glyphs are used
Online compressors get their impressive ratios by fixing both. Fubako does the same two things locally: images are downscaled to what their placement actually requires, and fonts are replaced with subsets containing only the glyphs in use.
Measured results
| Document type | Result |
|---|---|
| Scanned PDF (image-heavy) | -25% / -59% / -82% by preset |
| Office export with fully embedded fonts | Up to -88% (on par with major online tools) |
| Already-optimized PDF | ±0% — kept as-is, never degraded for nothing |
Safety checks so nothing breaks
The worst outcome of compression is "smaller, but broken". Before writing, Fubako verifies the result against the original:
- Every page's text must match exactly (search and copy preserved)
- Rendered output is compared — pages that visibly changed are rejected
- If the result would be even one byte larger, your original is used instead
How to use it
- Open the PDF in Fubako and click Compress in the toolbar
- Pick a quality preset (High / Standard / Smallest)
- Choose a destination — you'll see the result like "2.4 MB → 380 KB (-84%)"
FAQ
Is my original file kept?
Yes. Compression exports to a new file; the original is untouched.
What about digitally signed PDFs?
Rewriting the file invalidates signatures, so Fubako detects them and warns you before exporting.
Are forms and annotations preserved?
Fubako automatically skips font replacement in PDFs containing interactive forms, staying away from fragile structures.