How this PDF compressor works — and when to use it
Most of a big PDF's weight is images: a scanned contract, a photo-heavy report, a brochure. This tool re-renders every page as an optimised JPEG at a chosen resolution using pdf.js, then rebuilds the document with pdf-lib. For scanned and image-heavy files that routinely cuts size by 50–80%. Everything happens in your browser tab — the file is never uploaded.
There's an honest trade-off: because each page becomes an image, the text is no longer selectable or searchable. For a scan, that's no loss — it was already a picture. For a text document exported from Word or Google Docs, you're usually better off keeping the original (it's probably already small), or exporting it again at a lower quality.
Picking a level
- Strong — the smallest file. Great for getting a bulky scan under an email limit.
- Balanced — a good middle ground: noticeably smaller, still comfortable to read.
- Light — keeps pages crisp, with more modest savings.
Trying to hit an email limit?
Gmail and most providers cap attachments around 25 MB. Start with Balanced; if it's still too big, try Strong. If you only need a few pages, split the PDF first, then compress.
More on specific cases: compress a PDF for email, on a Mac, or on an iPhone.
Frequently asked
Is my PDF uploaded anywhere?
No. The PDF is rendered and rebuilt in your browser tab using pdf.js and pdf-lib. The file never leaves your device, and it works with Wi-Fi off after the page loads.
What kind of PDFs does this shrink most?
Scanned documents and image-heavy PDFs, where it can cut size by 50–80%. PDFs that are mostly text (exported from Word) are usually already small, so there's less to gain.
Will the text still be selectable?
No. This compressor re-renders each page as an optimised image, so text becomes part of the picture. Ideal for scans; if you need selectable text, keep the original.
Can I compress a password-protected PDF?
Only if it has no open password. Remove the password first, then compress.