No. Compression runs entirely in your browser. Your PDF never leaves your device, which is also why large files can take a minute on slower machines.

Balanced (300→150 DPI JPEG re-encode) is invisible on typical documents and is a great default. Pick Light (300 DPI) when you need near-original quality, or Extreme (72 DPI) for the smallest possible file, e.g. emailing a scan.

Standard, unlocked PDF files up to 100 MB are supported, one file at a time. Password-protected PDFs do not work yet; remove the password in your PDF viewer first, then compress the unlocked copy.

Scanned PDFs are pictures of pages, so their text can't be searched or copied. This option runs OCR (optical character recognition) on the scanned pages and adds an invisible text layer on top, making the compressed PDF searchable. Pages that already have text are left untouched, and the option only runs when you tick it. Recognition supports English and Indonesian.

Some PDFs are already tightly compressed. When that happens the tool tells you honestly instead of pretending. You can still download the processed copy if you need it.

PDF compression runs in current versions of Chrome, Edge, Firefox, Safari and other modern browsers with JavaScript enabled.