Optimize PDF
Repack a PDF's internal structure with object and cross-reference streams. Best on files written by older tools or saved with a long edit history. Runs entirely in your browser.
This tool repacks document structure only. It does not recompress images, so scanned or photo-heavy PDFs usually won't shrink much — most of their size is image data we leave untouched. Typical savings are 0–20%, and files that are already optimized may come out slightly larger.
Files stay on your device. Nothing is uploaded.
Frequently asked questions
How does this reduce a PDF's file size?
It re-saves the document using object streams and a compressed cross-reference stream, which pack the PDF's internal structure more tightly than older writers do. Text, vectors, fonts, and images are copied through unchanged.
How much smaller will my PDF get?
Usually 0-20%. Files produced by older tools, or ones carrying a long incremental-save history, benefit most. Files already written with object streams may not shrink at all, and small documents can come out slightly larger — the tool shows you the before and after so you can decide which to keep.
Why didn't my scanned document shrink?
Because almost all of its size is image data, and this tool does not touch images. Reducing a scan meaningfully means re-encoding its pages at a lower quality, which requires a tool that rasterizes the document. We'd rather tell you that than ship a slider that does nothing.
Can it open password-protected PDFs?
No. The PDF library we use in the browser cannot decrypt documents, so we detect encrypted files and stop rather than writing out a corrupted result. Remove the password or permissions restriction first, then run the file through.
Are my PDFs uploaded to a server?
No. The file is read and re-saved entirely in your browser using pdf-lib. It is never uploaded, and we never see it.
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This free tool is built and maintained by KSPR Technologies. We build web, mobile & AI products for clients.