Compress PDF Online
Reduce PDF file sizes while maintaining readability. 100% free, 100% private — nothing leaves your browser.
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How to Compress PDF Files Online
SmarterSources' PDF compressor reduces the file size of your PDFs by re-rendering each page as a compressed image and reassembling them into a new, smaller PDF. This works entirely in your browser — your files are never uploaded to any server.
How It Works
The tool uses pdf.js to render each page of your PDF at your selected DPI resolution, then converts each page to a compressed JPEG image. Finally, jsPDF assembles these compressed pages back into a new PDF. The result is a significantly smaller file that maintains readability.
Choosing the Right Quality
Low (72 DPI) produces the smallest files — ideal for screen-only viewing, email attachments, and web sharing. Medium (120 DPI) balances file size and quality well for most uses. High (150 DPI) keeps text sharp and is suitable for documents you might print.
Privacy Guarantee
Your PDFs are compressed entirely within your browser. No files are uploaded to any server. Your documents never leave your device.
Frequently Asked Questions
Will compression reduce the quality of my PDF?
Yes, there is a tradeoff between file size and quality. At Medium quality, text remains crisp and readable. Low quality works well for sharing but may show slight softness on detailed graphics. For text-heavy documents, even Low quality typically looks great.
Does this preserve selectable text?
The compressed PDF renders pages as images, so text will no longer be selectable or searchable. If you need selectable text, consider using the High quality setting for the best readability.
How much can I reduce the file size?
Typical reductions range from 30% to 80%, depending on the original PDF content. PDFs with high-resolution images see the biggest reductions. Already-optimized PDFs may see smaller improvements.
Is there a page limit?
No artificial limit. Very large PDFs (100+ pages) may take longer to process depending on your device, but there are no restrictions.