The PDF compression problem
PDF compression is one of those tasks that sounds simple until you try it. A 50 MB PDF won’t email — most providers cap at 25 MB and many cap at 10 MB. You want to get it down to maybe 5 MB without making the text unreadable or the embedded images blurry.
The compression engines vary widely. Some re-render the PDF through ghostscript on a server. Some just strip metadata. Some use image downsampling that destroys quality.
Free options
- iLovePDF — a server-side compressor that handles typical PDFs well. Files upload, are processed, and you download the result.
- Smallpdf — same model, polished UI, slightly higher quality results.
- PDF2Go — fine for casual use, but size reduction is modest.
- ToolConvoy’s PDF Compress — runs in the browser using pdf-lib. Files don’t upload.
ToolConvoy’s approach
The PDF Compress tool accepts a PDF and processes it locally. It applies:
- Metadata stripping — removes document properties (author, title, subject, keywords) and XMP metadata that bloats the file
- Image recompression — re-encodes embedded JPEG and PNG images at a target quality, downsampling where allowed
- Object stream optimization — restructures the cross-reference table to remove dead objects
For a typical PDF with text and a few images, you can expect 40-70% size reduction with no visible quality loss. For a PDF that’s mostly scanned images, the reduction depends on how aggressively you let the image recompression step run.
Privacy note
iLovePDF and Smallpdf both upload. If you’re compressing a confidential document — a contract, a tax return, a manuscript — the upload is a privacy cost. ToolConvoy’s compressor doesn’t upload.
Recommendation
For a private PDF: ToolConvoy.
For a casual PDF where privacy doesn’t matter: iLovePDF or Smallpdf produce slightly tighter compression for complex PDFs because their server CPUs are larger.