Secure Client-Side PDF Compression

Most competitors are secure in the sense that they use HTTPS and promise to delete your file after an hour — your document still reaches their servers. Here there is no server in the data path at all. The distinction is architectural rather than a policy commitment you have to trust.

Your file contents are never transmitted, so they cannot be logged or stored. Compression settings stay in local browser memory and are discarded when you close the tab. Standard anonymous page-view analytics may run, but they never see your documents, filenames or file sizes.

Yes. WebAssembly executes inside the browser sandbox with no filesystem or network access of its own. It can only touch the specific bytes you hand it and can only return bytes back. It is the same technology Figma, AutoCAD Web and Photoshop Web rely on.

Both, layered. Structural optimization — removing duplicate objects, dead revisions and metadata — is entirely lossless. Image downsampling and JPEG re-encoding are lossy, which is where the substantial savings come from. Text and vector graphics are never touched by either stage.

You can compress them, but be aware that any modification to a PDF invalidates its cryptographic signature — this is true of every compression tool, not just ours. If the signature must remain valid, do not compress the signed document.

Rarely, and it is usually counterproductive. The first pass already removes structural waste and downsamples images; a second pass mostly re-encodes already-degraded JPEGs, which loses more quality for negligible gain. Prefer a stronger preset on the original file instead.

Any modern browser with WebAssembly support: Chrome, Edge, Firefox, Safari, Brave, Opera and Arc, on desktop and mobile. Chromium-based desktop browsers are typically the fastest for very large documents.

There is no page-count limit. The practical constraint is memory rather than pages: a 500-page text document compresses easily, while a 500-page high-resolution scan may exhaust memory on a lower-spec machine. Closing other tabs frees up headroom for very large jobs.

No. Compression runs entirely inside your browser using WebAssembly. Your PDF is read into local memory, processed on your own CPU and written straight back to your downloads folder. No network request ever carries the file.

Less Compression favours quality with images near 200 DPI. Recommended is the balanced default at roughly 144 DPI. Extreme maximises size reduction at about 96 DPI. Target Size ignores presets entirely and searches for the best quality that fits your specified limit.