Compress a PDF: pdf.js renders every page, pdf-lib rebuilds a smaller file. Pick a quality preset, see the before and after sizes and download.
All processing happens locally in your browser. Your PDF never leaves your device.
Drop a PDF here or click to browse — one PDF at a time
This tool takes the rebuild-from-images route: Mozilla's pdf.js renders each page to a canvas, the canvas is re-encoded as JPEG, and pdf-lib assembles the results into a new PDF. Everything runs locally in your browser — there is no upload step.
| Preset | Render scale | JPEG quality | Best for |
|---|---|---|---|
| High quality | 1.5× | 0.82 | Scans you still want crisp on screen |
| Balanced | 1.0× | 0.70 | Most scanned and image-heavy PDFs |
| Smallest file | 0.75× | 0.55 | Attachments and upload portals with size caps |
It rebuilds your PDF from page images: pdf.js renders every page onto a canvas at the preset's resolution, each canvas is re-encoded as a JPEG, and pdf-lib assembles the JPEGs into a new PDF sized to the original pages. That raster pipeline is why scanned and image-heavy PDFs shrink so reliably.
No. Parsing, rendering, re-encoding and assembly all run in your browser with pdf.js and pdf-lib. Your PDF never leaves your device and no network request carries your file content.
Yes. Because every page becomes a flat image, text selection, search, links and interactive form fields are lost. The method shines on scanned documents, which have no selectable text to begin with — for searchable text PDFs consider a lossless optimizer instead.
Text-heavy or vector-graphic PDFs are already extremely compact, so a full-page JPEG of each page can end up larger than the original. The page-count and estimated megapixel readout hint at this: run another preset, and if it still grows, keep your original file.
High quality (render scale 1.5, JPEG quality 0.82) keeps the most detail. Balanced (scale 1.0, quality 0.70) is the right first try for most scans. Smallest file (scale 0.75, quality 0.55) pushes shrinkage hardest at visible softness. Compression estimates nothing up front — only running a preset shows the real output size, so use Try another preset to compare them without re-uploading.
If you just finished with PDF Compressor, the natural next steps are PDF Watermark, PDF Rotator, PDF Page Count, or browse every tool in Privacy File Tools.