Compress PDF
Reduce a PDF's file size by re-encoding each page at a lower image quality. Runs in this tab nothing is uploaded.
How this works
This tool renders each page to an image using pdf.js, re-encodes that image as a JPEG at the quality level you choose, and rebuilds a new PDF from those images with pdf-lib. This is the same technique most online compressors use, and it works especially well on scanned documents or PDFs with large embedded photos. One trade-off: text becomes part of the page image, so it's no longer selectable or searchable in the compressed file for documents where you need to keep real text, this isn't the right tool.
Common uses
Shrinking a scanned document before emailing it, reducing a photo-heavy report so it fits an upload limit, or archiving large PDFs with less disk space.