Compress PDF

Free online PDF compressor

Large PDF files can be awkward to share by email or upload to web forms with size limits. This tool rewrites your PDF to remove unused objects and optimise internal structures, producing a smaller file without degrading text or vector content. It runs entirely in your browser using pdf-lib, so your documents never leave your device.

How it works

The compressor loads your PDF, parses every object in the file, and rewrites the document from scratch. This process strips out orphaned objects, duplicate resources, and unnecessary metadata that accumulate as PDFs are edited repeatedly. Text, fonts, and vector graphics are fully preserved.

Common use cases

Shrinking scanned documents before emailing them. Reducing file size for upload to government or university portals with strict limits. Compressing exported reports that contain embedded images. Preparing PDFs for archival storage where space matters. Making large slide decks lighter before sharing with colleagues.

Tips

PDFs that are already well-optimised may not shrink much further. Files with many large embedded images benefit most from compression. Password-protected PDFs cannot be processed - remove the password first using a dedicated tool.