How this compression works
This tool renders every page of your PDF to an image at a reduced resolution, then re-saves the images inside a new PDF using JPEG compression. This is the same principle used by professional tools like Adobe Acrobat's "Reduce File Size" feature — it genuinely shrinks the image content, not just the metadata.
Step-by-step
- Upload your PDF. Click or drag your file onto the upload area.
- Choose a compression level. Balanced is the best starting point. Use Maximum for the smallest possible file, or High Quality when appearance matters more.
- Click Compress. Each page is rendered and re-saved. Progress is shown per page.
- Download and check. Open the result before sharing. Keep the original as a backup.
Compression level guide
- Maximum (72 dpi, 40% quality) — smallest possible file. Good for sharing documents on screen where sharp detail is not needed. Images will look soft. Can achieve 70–90% reduction on image-heavy PDFs.
- Balanced (120 dpi, 65% quality) — the recommended setting for most use cases. Looks good on screen and prints acceptably. Typically 40–75% size reduction.
- High quality (150 dpi, 82% quality) — near-original appearance. Modest size reduction of 15–40%. Best when the document needs to look sharp when printed.
What changes in the output?
Because each page is rasterised (converted to an image), the output PDF will not have selectable text. All content becomes part of the image. The visual appearance depends on the quality level you choose — at Balanced and above, most documents look very similar to the original on screen.
What types of PDF benefit most?
- Scanned documents — already images, compress very well.
- PDFs with photos — large JPEG images inside compress significantly.
- Exported reports and presentations — usually contain images that can be re-compressed.
Privacy
Your PDF is rendered and processed entirely in your browser using PDF.js and pdf-lib. Nothing is uploaded to any server at any point.