Compress PDF
Use this free online Compress PDF tool to shrink large PDFs by recompressing embedded images and stripping unused metadata. It is useful for emailing a PDF that exceeds the attachment size limit, uploading documents to a portal that caps file size, archiving scanned documents at a smaller footprint, or simply speeding up loading on a website. Drop your PDF into the upload zone, pick a compression strength, and download the smaller version — text remains crisp because only the embedded images are recompressed, not the text layer itself. Compression runs in your browser using pdf-lib so your documents never leave your device. Original PDF stays untouched.
Click to choose or drag & drop a PDF
Note
This tool flattens each page into a JPEG image, which dramatically shrinks scanned and image-heavy PDFs but converts text into pixels (no longer selectable). For text-only PDFs, savings are minimal.
How to Use This Compress PDF
Compressing a PDF takes a drop, a slider and a click.
- Drop the PDF into the upload zone or click to choose a file.
- Pick the compression strength — Light, Medium or Strong.
- Optionally tick 'remove metadata' to strip author, title and producer fields.
- Click Compress PDF and wait while the embedded images are re-encoded.
- Click Download to save the smaller file; the original PDF is untouched.
How This Compress PDF Works
Most large PDFs are big because of the images embedded inside them, not the text. A 50-page report with a few full-resolution photographs can easily be 30+ MB even though the readable text only takes a few hundred kilobytes. The tool uses the open-source pdf-lib library to walk every image object inside the PDF, decode it via the browser's built-in image decoders, draw it onto an off-screen Canvas at a reduced resolution and JPEG quality matching the chosen strength, and write the smaller image back into the PDF in place of the original. Light compression keeps the original resolution and just nudges JPEG quality down to 85%; Medium drops resolution to roughly 150 DPI at quality 75%; Strong drops to 96 DPI at quality 60%. The text layer is never touched, so readability is preserved. Optional metadata stripping removes the document's author, title, producer and creation date — small wins individually but they add up when applied with image compression. Because everything runs locally there is no upload, no rate limit, and confidential documents stay on your device.
Last updated: May 2026.
Frequently Asked Questions
Why is text no longer selectable in my compressed PDF?
Compression flattens each page to a JPEG image, replacing the original text layer with pixels. For searchable text, run the result through OCR.
Which compression level should I use?
Medium is a great default for most documents. Use Low only when file size is more important than legibility, and High for documents where appearance must stay crisp.
Will compression damage important details?
Lower compression levels can make small text blurry or introduce JPEG artefacts around fine lines. Try Medium first; if the result looks bad, drop back to High.
Can I undo compression?
No — once compressed, the original quality is gone. Always keep the source file as a backup.
Why doesn't it shrink my text PDF much?
PDF's text storage is already compact. Image compression doesn't help. For text PDFs, look for redundant fonts and images to remove — desktop tools handle this better.