The Best Free PDF Compressors
Need to shrink a PDF for school applications, jobs, or government portals? We reviewed and ranked the top free online and offline PDF compressors.
Siliph PDF Compressor
Best for Speed, Quality, and local privacy
Siliph provides a highly optimized browser-local PDF compression utility. Shrink files locally using advanced client-side processing, preserving image clarity and text outlines.
✓ Pros:
- Runs completely locally in browser memory (no uploads)
- Unlimited compression tasks with no paywalls
- Custom compression levels (high, medium, low)
- 100% ad-free workspace
✗ Cons:
- Very old scanned PDFs might require OCR before compression
Adobe Acrobat Online Compressor
Best for Industry-Standard Reductions
Adobe offers a free web-based compressor that provides excellent file size reduction. However, it enforces limit rules for non-subscribed users.
✓ Pros:
- Highly optimized file reduction algorithm
- Recognized industry leader
- Clears files from servers quickly
✗ Cons:
- Requires account signup for repeated uses
- Uploads documents to third-party Adobe cloud servers
iLovePDF Compressor
Best for Heavy File Size Reductions
iLovePDF is a popular online utility that offers three compression levels. It provides significant compression ratios but uploads files to public remote servers.
✓ Pros:
- Achieves massive size reduction ratios
- Simple, fast, and easy to use
- Supports batch compression
✗ Cons:
- Display layout is cluttered with tracking and banner ads
- Files are sent to cloud storage locations
How to get maximum PDF size reduction
Getting a PDF under target limits (like 200KB or 500KB) depends on the layout elements of the file:
- Image Downsampling: Scanned pages contain large raw images. Compression downsamples these to 150-72 DPI, dramatically reducing size while keeping text readable.
- Font Subsetting: Embedded fonts can occupy hundreds of kilobytes. Optimization subsets or replaces standard fonts with system font hooks.
- Removing Unneeded Objects: Metadata, bookmarks, and structural logs can be stripped from the raw PDF binary.
Shrink your documents securely
Try Siliph PDF Compressor today. Secure browser-local processing with zero paywalls.