Reduce PDF file size using pdf-lib's object-stream compression. Useful for shrinking large scanned documents before email, upload, or archiving. Runs in your browser, no upload.
PDFs balloon in size when they contain high-resolution scanned images, embedded fonts, or unoptimised metadata. Compression reduces file size by re-encoding object streams more efficiently. Substantial size reductions usually require image down-sampling — for that, image-based PDFs benefit most. Text-only PDFs are already nearly minimal.
Choose your PDF. The tool loads pdf-lib, opens the document with metadata-update disabled, and re-saves it with object-stream compression enabled. The compressed file downloads as compressed.pdf with the size reduction reported.
Use it before emailing PDFs (most providers cap at 25 MB), before uploading to platforms with size limits, before archiving large document sets, and when sharing through messaging apps where size matters.
For maximum compression on image-heavy PDFs, downsample images first: use ilovepdf.com/compress_pdf or Adobe Acrobat's Reduce File Size feature. This browser tool handles object-stream compression only — image down-sampling requires more complex processing.
10–30% for typical PDFs without image-heavy content. For scanned-image PDFs, dedicated image-compressing tools achieve 70–90%.
Object-stream compression is lossless. Image quality is unchanged because images aren't re-encoded by this tool.
Browser memory is the only limit. Most modern devices handle PDFs up to several hundred MB.
Explore more pdf tools on the tool hub — or jump straight to the Merge PDF, Rotate PDF, Unlock PDF.