How to compress a PDF

1. Upload the PDF

   Drop the .pdf into the "PDF file" field. Password-protected files are rejected — unlock them with PDF unlock online first.

2. No quality slider here

   Compression is structural, not visual: pdf-lib repacks streams and object tables. The tool does not re-compress images or down-sample fonts, so visual quality is unchanged.

3. Press Run

   Both an optimised and the original copy are considered; whichever is smaller is returned. The accompanying note tells you which strategy won.

4. Set expectations

   Image-heavy PDFs barely shrink with this tool — they need a graphics-aware compressor. Text-heavy PDFs from PowerPoint/Word exports often shrink 20–50%.