🗜️ Compress PDF
Reduce a PDF's file size by removing unused metadata and optimizing its internal structure — right in your browser.
About Compress PDF
Compression here reduces a PDF's file size without touching its visible content — no text, fonts, or images are altered. It works by rebuilding the file's internal structure: removing unused or duplicate objects, stripping unused metadata (things like editing history or embedded thumbnails some programs leave behind), and re-saving with more efficient object encoding. It's the right tool when a PDF is larger than it needs to be for what's actually on the page.
This runs through pdf-lib.js, which loads the PDF's object structure, removes anything not referenced by the actual pages, and saves the file with object-stream compression enabled — a PDF 1.5+ feature that packs multiple small objects together more efficiently than they were originally stored. This is a structural cleanup, not image recompression: embedded photos and scans are kept at their original resolution and encoding, so visual quality is unchanged.
Because of that, results vary a lot by source file. PDFs exported from Word, PowerPoint, or Google Docs often carry a surprising amount of structural bloat — duplicate font subsets, unused object references, verbose metadata — and can shrink noticeably. A PDF that's mostly high-resolution scanned images has little of that overhead to remove, so the size reduction there will be modest, since the images themselves, which make up most of the file, aren't recompressed.
Frequently asked questions
Will compressing reduce quality?
No — this method doesn't touch text, fonts, or images; it only removes unused metadata and optimizes the file's internal structure.
Why is the size reduction sometimes small?
PDFs that are already optimized, or made up mostly of already-compressed images, have little structural overhead left to remove.
Will this shrink a scanned document made of photos?
Only a little. Scanned PDFs are mostly embedded image data, and this tool doesn't recompress or downscale images — it only cleans up the PDF's structural overhead, which is a small part of an image-heavy file's total size.
Does compression remove document metadata I want to keep, like the title or author?
It removes unused internal metadata such as leftover editing history and thumbnail caches, not the document's visible title, author, or properties that were intentionally set — those are preserved.
Is it safe to compress a PDF I need to submit somewhere official?
Yes — since no text, fonts, or images are modified, the page content and appearance are identical to the original; only the file's internal packaging changes.