Is PDF compression private?

Yes. Compress PDF runs entirely in your browser using pdf.js and pdf-lib. The file does not leave your device.

How is this different from Images to PDF?

Images to PDF builds a new PDF from JPG/PNG photos. Compress PDF takes an existing PDF and makes that file smaller.

Why did my PDF barely shrink?

Scanned PDFs and files that are already heavily compressed have less room to improve. Try lowering render quality slightly or splitting very long documents.

Compress PDF Online — Free, In Your Browser

JPEG compression (canvas → PDF) 80%

Lower = smaller file, more soft/blocky pages. Higher = sharper pages, larger file. 100% = least JPEG compression (still JPEG, not lossless).

More compression Balanced No compression (100%)

Render zoom (pdf.js supersample) 150%

Pages are drawn larger than the output width, then downscaled before JPEG. Higher zoom = sharper text, slower + more memory (up to 500%). 100% = no supersample.

100% (faster) 150% 500% (max detail)

AVIF → JPEG bridge — when supported, try canvas→AVIF→JPEG per page and keep the smaller JPEG (AVIF still isn’t stored inside the PDF). Retry stronger if needed — if the first pass isn’t smaller, run one stronger pass (lower width + JPEG quality).

Compress PDF

🔍 Interactive Quality Inspection (Slide to Compare)

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Frequently asked questions

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