Compress PDF

Reduce the file size of any PDF by rasterising its pages to optimised JPEGs and repackaging them into a compact PDF. Choose Medium or High compression entirely on your device.

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Local processing

Compress PDF Online Free — Shrink PDF Files in Your Browser

Compressing a PDF is the practice of reducing its storage footprint without sacrificing too much visual fidelity. The compressor at PDFGuru renders each page using Mozilla's battle-tested pdf.js engine, rasterises the result onto a canvas, encodes it as a JPEG at a quality you control, and then re-packaging the pages into a fresh PDF using jspdf. Internal redundancy, oversized fonts and unused objects are stripped out automatically as part of the re-encoding pass.

Two presets are offered out of the box. Medium sets a JPEG quality around 0.55, which typically shreds a 5 MB scan down to about 1 MB while preserving good readability. High drops the quality to roughly 0.30, producing extremely compact files that remain legible on a phone screen but may show visible JPEG artefacts in photographs. A live slider lets you fine-tune the quality between 0.20 and 0.95 if you want full control.

Because the entire workflow executes locally, there is no upload step. A large PDF you would normally hesitate to send to a server — for instance a confidential legal brief — is safely processed inside your browser tab and the bytes never reach the network. This is especially valuable for professionals operating under restrictive data-handling rules.

The output PDF contains image-based pages, so searchable text layers are sacrificed in exchange for size. If you need searchable output, use the Extract Text tool afterwards and store it alongside. For documents that are already raster scans, the compress tool can typically produce 60%–85% file-size reductions.

Try the compressor above with any size of PDF — there is no upload limit and no per-day quota — and download the smaller file instantly without any watermark added by PDFGuru.

Compress PDF — Frequently Asked Questions

Scanned PDFs typically reduce 60–85% in size. Vector PDFs with embedded fonts reduce less dramatically because they are already optimised — expect 10–40% savings.
No — compression converts pages to raster JPEGs for size efficiency. To keep text content separately, use our Extract Text tool and store the .txt file next to the compressed PDF.
Yes. The slider ranges from 0.20 (maximum shrinking, visible artefacts) to 0.95 (near original quality). The Medium and High buttons just jump to common positions on the same slider.
Yes. After the page is fully loaded, all rendering, rasterising and packaging happens in your browser's JavaScript engine. You can disconnect from the internet and the compressor will still work.