PDF Compressor

How it works

Re-writes a PDF with Ghostscript using the screen, e-book, printer or prepress preset, or your own image resolution and JPEG quality. Shows the size before and after, can compare up to three presets side by side, and renders page 1 before and after so you can judge the quality. If the result is not smaller, you get the original back.

• The PDF is validated with qpdf and decrypted with your password if needed. Ghostscript (pdfwrite) then rewrites it: images are downsampled to the preset resolution and re-compressed, fonts are subset and compressed, duplicate images are stored once.
• Presets follow Ghostscript's -dPDFSETTINGS: screen ≈ 72 DPI images, ebook ≈ 150 DPI, printer and prepress ≈ 300 DPI (prepress keeps more colour information). Custom sets the colour/gray image resolution and the JPEG quality directly.
• Savings = 1 − new size ÷ original size. When a level does not make the file smaller (common for text-only or already optimised PDFs), the original file is returned for that level instead.
• Page 1 is rendered at the same size before and after (Poppler) so you can compare image quality and text sharpness.
• Dates and random IDs are removed from the output so the same input always gives the same file. Document title/author are kept; XMP metadata is removed.

Ghostscript re-creates the PDF: interactive elements such as form fields usually survive, but digital signatures become invalid and some rare features may be lost. Keep your original.