How browser-side PDF compression works
The tool renders every page to a canvas, exports it as a JPEG at your chosen quality, and rebuilds the PDF from those images. This trades selectable text for big size savings — a typical sweet spot is Medium (75% JPEG quality at 1.2× scale), which often cuts the file in half or more.
The big trade-off
Because the pages become images, you lose: text selection and search, embedded fonts, hyperlinks, form fields, and vector sharpness. If those matter, keep the original PDF or use a quality-preserving approach (downsample only embedded images, recompress with mozjpeg — both more complex than this tool offers).
When to use which quality
- High: minor savings, almost-original look — best when the PDF must still look polished.
- Medium: balanced — best for sharing receipts, scans, brochures.
- Low: aggressive — best for email attachments under 5MB or quick web previews.
Privacy
Compression runs in your browser using pdf-lib and the Canvas API. Your PDF never reaches a server.