Compress PDF
Drop a PDF, pick a level and click “Compress PDF” – you see straight away how much smaller the file gets. Everything runs in your browser; the PDF is never uploaded.
How it is calculated
Portals, application forms and mailboxes often limit file size – typically to 2, 5 or 10 MB. Usually scanned pages or phone photos inside the PDF are to blame. This tool compresses the PDF right in your browser and shows the size before and after.
How it works
- Drop or choose a PDF.
- Choose the method: “Recompress images” keeps text as text; “Save pages as images” compresses more.
- Choose the level: “Medium” is usually enough; use “Strong” when the size limit is tight.
- Click “Compress PDF”, compare before and after and download the new file.
What the two methods do
Recompress images: a PDF stores photos and scans as embedded image objects (ISO 32000-1, section 8.9.5). The tool scales JPEG and uncompressed colour or greyscale images down to at most 2,400 (light), 1,600 (medium) or 1,100 pixels (strong) on the long edge and saves them again at 85, 72 or 60 % JPEG quality – but only if that makes the image at least 10 % smaller. Text, fonts, links, bookmarks and form fields stay unchanged. CMYK images, masks and black-and-white scans (JBIG2/CCITT) are left as they are.
Save pages as images: every page is rendered as a JPEG at 150, 120 or 90 dpi and placed in a new PDF. This saves the most on PDFs with lots of vector graphics or embedded fonts – but text becomes a picture: not searchable, not copyable, and links and forms disappear. For documents that are only read or printed, that is often fine.
Honest limits
A PDF that is almost all text can hardly be compressed – the tool says so instead of handing you a bigger file. At “Strong”, small print in scans gets softer; check the result before sending it. Password-protected PDFs cannot be edited, and any change invalidates digital signatures.
Privacy
Processing runs entirely on your device with pdf-lib and pdf.js (both open source). The file is never uploaded – a real advantage for CVs, contracts and medical letters compared with online services.
Frequently asked questions
How can I compress a PDF for free?
Drop the PDF here, choose the “Medium” level and click “Compress PDF”. It is free, needs no account and never uploads the file.
How do I get a PDF under 2 MB?
Try “Recompress images” at “Strong” first. If that is not enough, “Save pages as images” at “Strong” usually saves the most: at 90 dpi an A4 page is only 744 × 1,052 pixels.
Does the text stay searchable after compressing?
With “Recompress images”, yes – only images change. With “Save pages as images”, text becomes part of an image: still readable, but no longer searchable or copyable.
Why does my PDF barely get smaller?
It probably contains mostly text, fonts or images that are already compressed. The tool only replaces an image if it shrinks by at least 10 % and never returns a bigger file.
Can I compress a PDF on an iPhone?
Yes, the page works in Safari on iPhone and iPad. Very large pages are capped at the iOS image limit of 16.7 megapixels.
Is compressing PDFs here safe?
Yes. The PDF is processed only in your browser and is never uploaded or stored anywhere.
Sources and legal basis
- Adobe – ISO 32000-1:2008 Document management – Portable document format (PDF 1.7)
- pdf-lib – Andrew Dillon (MIT)
- pdf.js – PDF rendering in the browser (Mozilla, Apache-2.0)
- pdf.js 6.3.289 licence (Apache-2.0)
- MDN – HTMLCanvasElement.toBlob() (JPEG encoding)
- MDN – createImageBitmap() (image decoding)
- Open-source licenses of the libraries used (MIT, LGPL-3.0)
As of:
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