Question 1

How does PDF compression work in the browser?

Accepted Answer

We re-save the PDF using object stream compression (which packs internal objects more tightly) and re-encode embedded raster images at a lower JPEG quality. Vector content and text are unaffected.

Question 2

How much can I compress my PDF?

Accepted Answer

Image-heavy PDFs typically shrink 40-70%. Text-only or already-optimized PDFs may only shrink 5-15% — there's nothing left to remove. The tool shows the before/after size so you can decide whether to keep the result.

Question 3

Are my PDFs uploaded to a server?

Accepted Answer

No. Compression happens entirely in your browser using pdf-lib. Your file is never uploaded.

Compress PDF