Compress PDF
Rebuild and optimise a PDF to trim its size — entirely within your browser.
Compress PDF
🔒 Your PDF is processed entirely in this browser tab (pdf-lib + Mozilla pdf.js) — it is never uploaded, so confidential documents stay on your device.
- ScansA scanned page is a full-page photo. Re-rendering at 150 dpi is still crisp on screen and in print, and usually cuts size by 60–90%.
- Text PDFsExported from Word or Google Docs they are already compact — the lossless option only tidies the file structure.
- Email limitsGmail 25 MB, Yahoo 25 MB, Outlook.com 20 MB, iCloud 20 MB, Microsoft 365 35 MB by default — and attachments grow ~33% when sent.
- PrivateOnline compressors upload your document; this one renders pages in your browser with Mozilla's pdf.js.
Provider limits checked October 2026.
Runs in your browser — nothing you enter is uploaded or stored.
Scratchpad auto-saved
How it works — in four simple steps
No signup and nothing to install — it all runs in your browser.
Choose a PDF
Drag in or select the PDF you want to compress; the tool shows its current size.
Compress
Press Compress — the file is rebuilt locally with a more efficient structure.
Review the savings
Check the original vs compressed size and the percentage reduced.
Download
Download the smaller PDF, ready to send under an email or upload size limit.
Scanned PDFs shrink the most with Balanced (150 dpi); text-only PDFs are usually small already — use lossless to keep text selectable.
Features
Shrink a PDF, keep it readable
Rebuilds the document with a tighter internal structure so it downloads and emails faster, with no visible quality loss.
Lossless rebuild
Removes unused objects and re-serialises the file — text stays crisp and pages are unchanged.
Private by design
The PDF is compressed in your browser and never uploaded, safe for confidential documents.
Before-and-after size
See the original size, compressed size and percentage saved so you know the result at a glance.
About the Compress PDF
PDFs accumulate overhead — unused objects, redundant metadata, and an inefficient internal layout — that inflates their size. Compressing rebuilds the file with a tighter structure so it downloads and emails faster, without changing how it looks.
Load your PDF and the tool re-parses it and re-serialises it using object streams, a compact way of packing the document's internal objects, then reports the before-and-after size. This is a safe, lossless optimisation: text stays sharp and pages are untouched.
Everything runs in your browser, so the file is never uploaded. Note that if most of a PDF's weight is high-resolution images, structural compression can only do so much — down-sampling or re-encoding those images (using an image compressor first) yields the biggest savings. Already-optimised PDFs may shrink little, which the tool will tell you.