- Is my PDF actually uploaded anywhere?
- No. The entire process runs inside your web browser using JavaScript. Your file never leaves your device — not to our servers, not to any third-party service. You can even disconnect from the internet after the page loads and it will still work. This makes it safe for confidential documents such as contracts, medical records, or financial statements.
- Why are scanned PDFs so large, and how does this fix it?
- Scanners typically embed each page as a full-resolution lossless image (300–600 DPI, PNG or TIFF-equivalent). A single A4 page at 300 DPI is roughly 2,500 × 3,500 pixels — about 8 MB before any compression. This tool re-renders each page at a lower DPI (e.g. 150 DPI = 1,240 × 1,750 px, ¼ the pixel count) and saves it as a JPEG at the chosen quality level. JPEG compression ratios for scanned text are typically 10:1 to 20:1, while the document remains perfectly legible. The combined effect is an 70–90% reduction in most cases.
- Will the text still be readable after compression?
- For typical office documents, contracts, and forms scanned at A4/Letter size, 150 DPI at medium quality (0.60) produces a file that looks crisp on screen and prints cleanly at 100%. Go down to 100 DPI if you only need on-screen legibility. 72 DPI is suitable for archival reference copies viewed on screen only. If the original scan was at a very high DPI (600+), even 150 DPI output will look excellent because you are starting from very sharp source pages.
- Does this work on text-layer (non-scanned) PDFs?
- Yes, but the benefit is smaller. Text-layer PDFs store text as vectors (very compact) and only embed images for photos or logos. Re-rendering them to JPEG converts the text to pixels, which may actually make the file larger — and you lose the ability to copy or search text. For those PDFs, use a dedicated PDF optimizer instead. This tool gives the best results on purely image-based scanned documents.
- Is there a file size or page count limit?
- There is no hard limit imposed by the tool — it depends on your browser's available memory. In practice, most browsers on a modern laptop handle 50–200 page PDFs up to about 100 MB without issue. Very large files (200+ pages or 200+ MB) may run slowly or exhaust browser memory. If you hit problems, try compressing in smaller batches by splitting the PDF first.