PDF Compressor
Reduce PDF file size entirely in your browser.
How this works (Browser Limitation)
Because this runs locally, we cannot rewrite the internal PDF objects like a desktop tool. Instead, we convert each page into a compressed image and build a new PDF. Resulting text will not be selectable. This is best for scanned documents, forms, or image-heavy PDFs.
Drag & drop files here
or click to browse from your device
Comprehensive Guide to In-Browser PDF File Compression
The PDF Compressor reduces the storage footprint of heavy, image-rich PDF files directly inside your browser. Designed for students, remote professionals, and legal teams, it optimizes document rasterization, adjusts rendering scales, and recompresses embedded imagery to create compact, email-ready files without exposing confidential data to external servers.
Popular Real-World Use Cases
Email Attachment Size Limits
Compress 30MB+ scanned PDF bundles under Gmail's 25MB or Outlook's 20MB attachment caps without needing third-party cloud links.
Real Estate & Loan Application Portals
Shrink multi-page mortgage applications, lease agreements, and bank proof-of-funds packages to satisfy strict portal upload thresholds.
eReader & Mobile Tablet Storage
Optimize bulky digitized textbooks, slide decks, and whitepapers for smooth scrolling and minimal memory consumption on mobile devices.
How In-Browser Processing Works
Browser security sandboxes prevent direct binary manipulation of low-level PDF stream dictionaries. Instead, our client-side engine renders each PDF page into a high-DPI canvas buffer using Mozilla's pdfjs-dist, applies adjustable JPEG compression curves to the rendered visual layers, and reconstructs a brand-new, highly optimized PDF using pdf-lib.
Pro Tips for Best Results
- This tool is exceptionally effective on scanned documents, photo portfolios, and invoice scans.
- For scanned text documents, a Resolution Scale of 1.5x with a Quality of 50–60% provides the sweet spot of crisp readability and minimal file size.
- Note that converting vector PDF pages to optimized raster images makes the resulting text non-selectable, ideal for final-form archive files.
How It Works
Select PDF
Drag in your heavy or scanned PDF document.
Processed on your device
Pages are rendered, scaled, and recompressed locally using pdfjs-dist and pdf-lib.
Download PDF
Instantly save your compact, email-ready PDF file.
Frequently Asked Questions
Why does client-side PDF compression make text unselectable?
Because browsers execute inside strict sandboxes without native desktop ghostscript binaries, each page is rasterized onto a high-resolution canvas before JPEG re-encoding. This produces massive size reductions for image-heavy documents while sealing the visual layout.
How do I ensure scanned text remains readable?
Keep the 'Resolution Scale' slider at 1.5x or higher. This ensures the canvas renders sufficient dots-per-inch (DPI) so that small print, signatures, and fine lines remain perfectly legible.
Why did my purely text-based PDF get larger after compression?
Vector PDFs containing only digital text and fonts are already tiny (often <100KB). Converting them into high-res images will increase their size. This tool is specifically intended for scanned documents, presentations, and image-heavy PDFs.
Can I compress password-protected PDF files?
Encrypted PDFs must be unlocked before client-side rendering. If your document requires an open password, unlock it prior to compression.
Is my file uploaded anywhere?
No — everything happens in your browser, your file never reaches a server.
Do I need to create an account?
No, no sign-up required.
Is this really free?
Yes, no hidden charges, no watermark on your output.