Compress PDF for Email Attachments

Gmail and Google Workspace allow 25 MB, Outlook.com allows 20 MB, Yahoo Mail 25 MB, and most corporate Exchange servers are configured between 10 MB and 20 MB. Because attachments are Base64-encoded in transit they grow roughly 33% on the wire, so aim for about 70% of the stated limit to be safe.

Switch to Extreme mode, or use Target Size mode and enter the exact ceiling you need. If the document is a long scan, consider splitting it into several smaller PDFs — a 200-page scanned book will not compress into a 10 MB attachment without becoming unreadable.

Yes. All processing runs in WebAssembly inside your browser tab. The file is read into local memory, optimized and written back out — no network request carries your document, so there is nothing to intercept, log or retain. You can even disconnect from the internet after the page loads and it still works.

Text always stays sharp because it remains real vector text rather than an image. Embedded photographs are downsampled and re-encoded, so quality loss scales with how aggressive a preset you choose. Less Compression is visually near-identical to the original.

Yes. Drop in as many files as you like and they are queued automatically. Processing is deliberately sequential rather than parallel: compressing several large PDFs simultaneously would compete for memory and can crash the browser tab, so each file is handled in turn.

There is no page-count limit. The practical constraint is memory rather than pages: a 500-page text document compresses easily, while a 500-page high-resolution scan may exhaust memory on a lower-spec machine. Closing other tabs frees up headroom for very large jobs.

Your PDF was probably already optimized — for instance exported by Acrobat with compression enabled, or generated as pure text with subset fonts. When we cannot beat the original we deliberately return your untouched file rather than a worse one.

It depends on the content. Scanned or image-heavy documents commonly shrink by 70–95%. Text-only PDFs that were already optimized may only drop 5–20%, since there is little redundant data left to remove.

Any modern browser with WebAssembly support: Chrome, Edge, Firefox, Safari, Brave, Opera and Vivaldi, on desktop and mobile alike. There is no minimum specification beyond that — older or lower-powered devices simply take longer on large documents.

Progress tracks pages completed, not time elapsed, and pages differ enormously in cost. A page holding one large photograph takes far longer than ten pages of plain text, so the bar appears to stall. It is still working — the Web Worker keeps the interface responsive throughout.