Every time you upload a PDF or image to a random “free” compression site, you’re handing over the full file (sometimes including hidden metadata like GPS location, device info, and embedded text) plus your IP address and usage data.
You have no idea how long it’s stored, logged, or reused. Compression doesn’t require a server; it can run entirely in your browser.
Witty University built a simple local HTML tool that compresses PDFs and images 100% offline, nothing gets uploaded: https://university.witty.computer/product/universal-local-compressor-private-pdf-image-optimizer-runs-100-in-your-browser/
Privacy is basic hygiene.
I work in Infosec and blocking these sites is an unending game of whackamole.
Compression doesn’t require a server; it can run entirely in your browser.
… why should it even require a browser?
It is a perfect honeypot. Do local compression for the majority, but if the IP comes from a government IP block, serve a different page and upload…
Just in case somebody’s trying to compress the unredacted Epstein files. Gotcha.
Probably for people who can’t / don’t want to install something on their computer. It’s easier to say “bookmark this page instead of that page” than to get people to install a local app.
Also this way you can use the same tool across desktop and mobile
Or save yourself $15 and just make a function to something that you probably already have on your Linux system:
shrink_pdf () { if [[ $# -ne 2 ]]; then echo 'Usage: shrink_pdf <input file> <output_file>' 1>&2; echo ' make sure to enclose file name in quotes' 1>&2; echo ' if it has spaces' 1>&2; return; fi; gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/printer -dNOPAUSE -dQUIET -dBATCH -sOutputFile="$2" "$1" }Change options as you want, and run it like:
shrink_pdf Original.pdf Compressed.pdf


