Compress a PDF. Know the tradeoff first.
This tool re-draws each page as an image at a quality you pick, then rebuilds the PDF. That genuinely shrinks scans and photo-heavy files - but text in the output becomes non-selectable and non-searchable. For many uploads (portals, email attachments) that is fine. If you need selectable text, do not compress this way.
Honest limits: pages are re-rendered as images, so the output loses selectable text and sharp vector edges, and a text-only PDF may not shrink much (it was already small). Scans and phone-photo PDFs shrink the most. The original file is never modified.
Compression runs fully inside your browser with the open-source pdf.js and pdf-lib engines. Encrypted or password-protected PDFs cannot be processed - remove the password first.