Reduce the file size of a PDF right here in your browser — perfect for shrinking scanned and image-heavy documents so they're easy to email and upload. Pick a PDF, choose how hard to compress, and download the smaller file. Nothing is ever uploaded — your document stays on your device. No signup, no watermarks.
This tool shrinks PDFs by re-compressing their pages. When you need to keep selectable text, OCR scans, edit pages, or process whole folders, get Kaizen OCR & PDF for Windows — a full offline PDF toolkit that does far more than any browser tab can:
Making a PDF smaller takes just a few seconds, and everything happens right here in your browser — your file is never uploaded:
Honest note: this method re-encodes each page as an image, so the new PDF's text is no longer selectable. It works best for scanned and photo-heavy PDFs — a file that is mostly plain text is already small and may not shrink much.
Most online "compress PDF" sites upload your document to their servers to do the work. This one doesn't. It uses Mozilla's open-source PDF.js engine to render your pages and pdf-lib to rebuild a smaller PDF — entirely in your browser. Your file never leaves your device, and you can even disconnect from the internet after the page loads and it still works. For heavier, repeatable jobs on Windows — keeping selectable text, extracting real text with OCR, editing and merging PDFs, or processing folders of files in bulk — try Kaizen OCR & PDF.
Yes — completely free and unlimited, with no signup and no watermarks. It runs locally in your browser, so you can compress as many PDFs as you like.
No. The compression happens entirely inside your browser using JavaScript and the open-source PDF.js and pdf-lib libraries. Your PDF never leaves your device and is never sent to any server, which keeps private and confidential documents fully private.
Each page is rendered to an image and re-encoded as a JPEG at the quality level you choose, then a new PDF is rebuilt from those images. This works best for scanned or image-heavy PDFs. Because pages become images, the text in the new PDF is no longer selectable.
You control the trade-off with three levels — Strong for the smallest file, Recommended for a good balance, and Light for the best quality with a more modest size reduction. Pick a stronger level for the smallest size, or Light to keep pages looking crisp.
This method shrinks scanned and photo-heavy PDFs the most. A PDF that is mostly plain text is already small and highly optimized, so re-encoding its pages as images may not reduce the size much — and could even increase it. For those, try a lighter level or keep the original.
Yes. Once the page has loaded, the compression runs entirely on your device. You can disconnect from the internet and it will still work, because nothing is uploaded.