Compress a PDF — losslessly, without uploading it
An honest word before you start: this is a lossless optimizer, not a magic shrink ray. It runs qpdf — a well-established open-source PDF tool compiled to WebAssembly — right in your browser, restructuring the file with object streams and recompressed internal data. Nothing visible changes: text, images, and fonts are untouched, so the output is pixel-identical to the input. Typical savings run 5–30%, best on PDFs generated by office software with inefficient internal structure. If your PDF is mostly large scanned images, expect little or nothing — the images are the bulk of the file, and shrinking them would require lossy recompression this tool deliberately avoids. The upside of that honesty: quality is guaranteed, and because the whole job runs locally, your document is never uploaded. Input and output sizes are shown side by side, so the benefit is never a mystery.
How it works
- Drop a PDF below or click to choose one.
- qpdf rewrites the file structure losslessly — content and quality are untouched.
- Compare the input and output sizes shown, then download name-optimized.pdf.
Frequently asked questions
How much smaller will my PDF actually get?
Typically 5–30%, and honestly, sometimes near zero. Savings come from restructuring the file — object streams, recompressed metadata and content streams, removed slack — so PDFs from word processors and report generators shrink most. A PDF that is essentially a container for big scanned images will barely budge, because the images dominate its size and this tool will not degrade them.
Will the compressed PDF look any different?
No — that is the guarantee of lossless optimization. Every character, image, and vector shape is preserved exactly; only the file’s internal plumbing is reorganized. If another tool promises dramatic shrinkage of scanned PDFs, it is downsampling your images. This one never does.
Is my PDF uploaded for compression?
No. qpdf is compiled to WebAssembly and executes inside your browser, the same way it would run on your own command line. Financial statements, contracts, and medical documents are processed entirely in local memory — no server, no upload, and it works offline once the page has loaded.
What is qpdf?
qpdf is a mature, widely used open-source command-line tool for structural PDF transformations — the kind of software packaged in every major Linux distribution. Here it runs as WebAssembly in your browser tab, which means you get a trusted, battle-tested optimizer without installing anything or sending your file anywhere.