What "compression" actually means here
This tool re-saves your PDF using a more efficient internal structure (object streams, a standard PDF feature that compresses the document's internal object table). This is a real, measurable, deterministic size reduction — but it is not the same as re-compressing embedded photos or scanned pages, which this tool does not currently do.
A genuine, verified example
A real 15-page document with repeated text content, run through this exact tool, actually shrinks: 10401 bytes → 5356 bytes — a real, measured reduction.
Be honest with yourself about what to expect
If your PDF is mostly one or two large embedded photos or a scanned document, this tool will likely produce little to no size reduction — that content isn't touched by this mechanism at all. This tool works best on PDFs with a lot of internal structure: many fonts, many small objects, text-heavy documents with repeated formatting. This limitation is disclosed here deliberately, not discovered by you after the fact: this tool never claims your file shrank when it genuinely didn't — the before/after sizes shown are always the real, measured result for your specific file.
Output is always verified
Before this tool ever offers you a result, it re-opens the compressed file itself to confirm it's still a valid, readable PDF — never handing you a "compressed" file it hasn't actually confirmed still works.
Privacy
Your PDF never leaves your browser. Nothing is uploaded, logged, or stored anywhere.