Option 1 — Preview (built into macOS)
Every Mac can compress a PDF without any download:
- Open the PDF in Preview (double-click it in Finder).
- Choose File → Export…
- In the Quartz Filter dropdown, pick Reduce File Size.
- Click Save.
It's convenient, but the Reduce File Size filter is a single fixed setting. On some PDFs it barely helps; on others it's too aggressive and leaves images looking soft. There's no slider to dial it in, and no preview of the result size before you save.
Option 2 — the browser (more control, still private)
The Unfuss PDF compressor runs in Safari or Chrome and processes the file on your Mac — nothing is uploaded. Unlike Preview, it offers three compression levels so you can trade size against sharpness, and it shows the before/after size so you know exactly what you got.
- Go to unfuss.app/compress-pdf in your browser.
- Drag your PDF from Finder onto the drop zone.
- Pick Balanced (good size, readable) or Strong (smallest).
- Download the result — it never left your Mac.
It's best on scanned and image-heavy PDFs, which is exactly what usually needs shrinking. Text-only PDFs are already small.
Which should you use?
- Just need it done fast, don't mind the result? Preview is right there.
- Want to control how small, or hit a specific email limit? Use the browser tool's levels.
- Handling something confidential? Both keep the file local — Preview by definition, and Unfuss because it never uploads.
Frequently asked
How do I compress a PDF on a Mac for free?
Two free ways: open the PDF in Preview and use File → Export with the Reduce File Size Quartz filter; or use a browser tool like Unfuss, which adds compression-level control and never uploads your file.
Why does Preview's Reduce File Size make my PDF blurry or barely smaller?
Preview's default filter is one fixed setting — sometimes too aggressive, sometimes barely effective. A tool with adjustable levels lets you find the right balance for your document.
Is my PDF uploaded when I use Unfuss on my Mac?
No. Unfuss runs in your browser, so the PDF is compressed on your Mac and never sent to a server.
Does this work on any Mac?
Yes. The browser method works on any Mac with Safari, Chrome, or Firefox — Intel or Apple Silicon, any recent macOS version.