You have a 30 MB PDF that won't fit in an upload form, is too large to email, or simply takes up unnecessary space. The good news: both Mac and Windows include free built-in tools to shrink it — no extra software required. And if you want the best result without risking your privacy, there are also browser-based options that process everything locally.
macOS's Preview app has a built-in Quartz filter that reduces PDF file size automatically when exporting. It is the fastest method on Mac and requires nothing to install.
Typical result: 40–70% reduction for PDFs containing images. Text remains selectable and searchable.
⚠️ Preview limitation: the "Reduce File Size" filter applies fairly aggressive compression and can visibly degrade images inside the PDF, especially photographs. Always preview the result before sharing the compressed file.
If the standard Reduce File Size filter degrades quality too much, you can create your own filter using the ColorSync Utility app:
Windows does not have a PDF compressor equivalent to Mac's Preview, but you can use the built-in PDF printer:
Typical result: 20–40% reduction. Less aggressive than Mac's Preview filter, but text remains selectable.
If your PDF was generated from a Word document, open it directly in Word (it converts automatically) and re-export with the "Minimum size" option:
If you do not want to use system tools, or the result is not good enough, the most private alternative is a tool that processes the PDF directly in your browser — without sending it to any server.
ComprimirPro processes your PDF 100% in your browser. It is never uploaded to any server, so there is no risk of data leakage. Ideal for contracts, invoices, and confidential documents.
Drop your PDF, adjust quality, and download in seconds. No sign-up, no limits, no file uploads.
⚡ Compress my PDFIf you have an Adobe Acrobat Pro subscription, it is the method with the most control and best quality:
Acrobat Pro also offers File → Reduce File Size, which is faster but less configurable.
| Method | OS | Typical reduction | Quality | Privacy |
|---|---|---|---|---|
| Preview (Mac) | Mac | 40–70% | Medium | ✅ Local |
| ColorSync custom filter | Mac | 30–60% | High | ✅ Local |
| Microsoft Print to PDF | Windows | 20–40% | High | ✅ Local |
| Word "Minimum size" | Windows | 30–60% | Medium-high | ✅ Local |
| ComprimirPro (online) | Both | 50–80% | Configurable | ✅ Local (browser) |
| Adobe Acrobat Pro | Both | 30–70% | Very high | ✅ Local |
No, vector text remains perfectly legible and selectable. What may degrade are images embedded in the PDF, which are recompressed with higher loss.
It depends on the type of protection. If the PDF only has an editing password but can be opened without one, the methods above work. If it requires a password to open, you need to unlock it with the correct password first.
If the PDF is already optimized or contains mainly vector text (no embedded images), additional compression is minimal — the file is already as compact as it can be. The biggest reductions come from PDFs containing uncompressed images or scanned pages.
For sensitive documents (contracts, IDs, banking information), always use local methods: Preview on Mac, Print to PDF on Windows, or ComprimirPro in the browser. Avoid online tools that upload your file to their servers.