Compress PDF
Free PDF compressor. Shrink PDF file size by re-saving with tighter internal structure, right in your browser. Honest, private, fast, no signup.
About this tool
Oversized PDFs bounce off email limits, upload slowly and eat phone storage. A PDF compressor shrinks the file so it is easier to send, share and store, while keeping every page readable.
This free tool re-saves your PDF with a tighter internal structure, right in your browser. To be fully honest: client-side compression mainly reduces file overhead, so text-heavy PDFs shrink nicely while PDFs made of big scanned images may only get a little smaller. Your file never leaves your device.
How to use
Choose the PDF you want to shrink and click Compress PDF. The tool rebuilds the file with compressed object streams and shows you the new size. Download the result and compare it with the original.
If the result is still too big, the pages are probably large images. In that case, convert the pages to JPG at lower quality first, then rebuild the PDF. For most office documents, though, one click is enough.
The math behind it
A PDF stores its content as numbered objects: fonts, page descriptions, metadata and images. Many PDFs, especially ones exported from office software, store these objects loosely with duplicated data and no compression on the container itself.
This tool parses the whole document and writes it back out using object streams, which pack objects together and deflate them. The visible content is untouched, so nothing looks different, but the redundant overhead disappears. That is why text documents can shrink dramatically while photo scans barely change.