Compress PDF — shrink scanned files in your browser
Make scanned and image-heavy PDFs smaller — privately, with no uploads.
This tool runs entirely in your browser. Your files are never uploaded — they stay on your device.
Choose file
or drag and drop
Big PDFs are usually big because of the images inside them — scanned receipts, photographed contracts and image-only exports. This tool re-renders each page at the quality you choose and rebuilds a lighter document, all inside your browser, so the file never leaves your device.
Be aware that pages are flattened to images, so selectable text becomes part of the picture. That makes this ideal for scans and screenshots, but a poor fit for text documents where you need to keep copyable, searchable text.
How it works
When you drop a PDF here, it is loaded with pdf.js, the same rendering engine that draws PDFs inside Firefox. Each page is painted onto an HTML canvas at the resolution and quality you pick, then exported as a compressed JPEG. Those page images are stitched back together into a fresh document with pdf-lib, and the result is handed to you as a download.
Every one of those steps runs in JavaScript inside the tab you have open. The file is read with the browser's File API, processed in memory, and the new PDF is produced locally. Nothing is sent to a server, there is no account, and closing the tab wipes everything from memory. That is what makes it safe to use on contracts, medical records, ID scans and other documents you would never want sitting on someone else's hard drive.
When to use it
This tool shines on PDFs that are large because of pixels rather than text: phone photos of paperwork, flatbed scans, screenshot exports, and image-heavy brochures. Those are exactly the files that strain email attachment limits or upload forms, and re-rendering them at a lower quality can shrink them dramatically.
It is the wrong tool for a born-digital document, such as an invoice exported from accounting software or a report written in a word processor. Flattening those pages to images discards the crisp vector text and can leave you with a file that is similar in size, or even larger, while losing the ability to select, copy and search the words. If you need the text to stay live, keep the original and reach for a text-preserving optimiser instead.
Tips
Start one quality step down from the highest setting and check the result before going lower; scans are often still perfectly readable well below maximum quality. Zoom in on small print and any signatures to confirm they are legible before you rely on the compressed copy.
The size comparison shown after compressing tells you whether the trade-off was worth it. If a page looks blocky or text is fuzzy, step the quality back up and run it again. Because the whole process is local and free, re-running with different settings costs you nothing but a moment, so it is worth experimenting to find the smallest file you are still happy to read and share.
How to use Compress PDF
- Drop your PDF onto the box above or click to browse for it.
- Pick a quality level — lower quality means a smaller file.
- Click “Compress PDF” to re-render every page in your browser.
- Compare the original and new size, then download the compressed PDF.
Frequently asked questions
Is my PDF uploaded to a server?
No. The file is read, re-rendered and rebuilt entirely in your browser. Nothing is uploaded, so it is safe for confidential and personal documents.
Why does my text stop being selectable after compressing?
Compression works by rendering each page to an image and rebuilding the PDF from those images. This shrinks image-heavy files well, but it flattens text into the picture, so it is no longer selectable or searchable.
Which PDFs compress best?
Scanned documents, photos and image-only PDFs see the biggest savings. Plain text PDFs may not shrink — and can even grow — so this tool is not recommended for them.
What if the file barely gets smaller?
Try a lower quality level. If a PDF is already mostly text or well-optimised images, there is little left to remove and the result may be similar in size or larger.