Compress PDF

Most of a PDF's size lives in its images. A 50 MB report is usually 48 MB of pictures and 2 MB of text. Compressing a PDF effectively means recompressing the images at a lower bit-depth, downsampling their resolution, or — at maximum settings — converting them to a more space-efficient format.

SwitchPDF uses Ghostscript's PDF/Distiller pipeline when it is available on our server, which is the industry-standard tool for PDF optimization. Ghostscript walks every page, finds the embedded images, downsamples each one to the target resolution (72 DPI for high compression, 150 DPI for medium, 300 DPI for low), and replaces them in the output. It also subsets embedded fonts, drops unused objects, and rebuilds the cross-reference table for a leaner file.

If Ghostscript is not available we fall back to pdf-lib-based optimization — slower image processing but still effective for documents that are primarily text. Both paths produce a valid, fully compatible PDF that opens in Adobe Reader, Apple Preview, Chrome, Firefox, and every other standard viewer.

Realistic expectations: PDFs that are heavy on photos compress 60–80% on high settings. Text-heavy reports compress 10–30%. Already-optimized PDFs (e.g. from "Save as PDF" with downsampling on) may only compress a few percent more. The tool tells you exactly how much smaller the output is so you know before you download.