Compress PDF without losing quality
Reduce PDF file size while keeping text crisp and images sharp. Content-aware compression preserves what matters. Free.
'Lossless compression' is technically misleading for PDFs — true mathematical losslessness is rare. What you actually want is compression where the loss is invisible at normal viewing. PDFOnly's compressor delivers exactly that: text glyphs are kept at full vector resolution (so they remain perfectly sharp at any zoom), and image downsampling is calibrated to be invisible at normal screen viewing.
Use the Low preset for the most quality-preserving compression — typically 30-50% size reduction with imperceptible image change. The Recommended preset doubles the savings (60-80% reduction) and is still invisible at 100% screen zoom; only at 200% or higher do you start seeing softness in photographic content. For text-heavy documents (contracts, reports, books), even High compression is essentially lossless because there are no images being downsampled.
Frequently asked questions
How can compression be 'lossless' if it reduces file size?
Strictly speaking, downsampling images is lossy. But 'visually lossless' means the loss is below your eye's threshold to detect at normal viewing distances. We use perceptual research-backed parameters so even the Recommended preset is invisible to most users.
Which preset should I use for archival?
Low. Archival means you might zoom in or print at high resolution years later, so preserve quality. Modest size reduction (30-50%) is a small price for peace of mind on important documents.
Is there truly lossless PDF compression?
Yes — PDF/A linearization, font subsetting, image stream re-encoding without quality change. We do all of these as part of every preset (savings: usually 5-15%). The Low preset stops there. Higher presets add image downsampling, which is the technically lossy part but visually imperceptible at default settings.