Say your email provider caps attachments at 25MB and the portfolio PDF you exported from a design tool clocks in at 60MB, mostly because of high-resolution photos. Or a job application portal rejects your resume because it's "too large", even though it's only a few pages — usually because it was scanned at high resolution instead of exported from a word processor. That's when Compress PDF earns its place: shrinking a file so it fits under a limit, without installing anything and without uploading it anywhere.
Compress is the wrong tool if your file is large because it has pages you don't need — trim it with Remove Pages first, since fewer pages plus compression beats compression alone. And if the goal is to combine files rather than shrink them, that's the Merge guide.
Step-by-step: compressing a PDF in the browser
- Note your current file size before you start, so you can judge the result.
- Open the Compress PDF tool, or click the "Compress PDF" card on the home page.
- Click the drop zone or drag in your file. Select one PDF: the tool compresses the first file in your selection.
- Choose a compression level. Recommended scales down very large photos and re-saves them at a good JPEG quality. Strong goes further, with smaller and lower-quality photos. Both keep text, fonts and vector graphics untouched. Maximum turns every page into an image, which shrinks scans the most but makes text unselectable.
- Click "Process now." At the Recommended and Strong levels, the tool first re-saves the photos embedded in the PDF, then uses qpdf, a PDF library compiled to WebAssembly, to rewrite the file structure with maximum compression and without unused objects.
- The status line shows the size before and after, and your browser downloads compressed.pdf. If the result isn't smaller than the original, nothing is downloaded and you'll see a message saying the file is already well optimized.
- Open the result next to the original and zoom in on the photos. If they look too soft, run the original again at a lighter level.
Common mistakes
- Choosing Maximum for a document that needs selectable text. Maximum is meant for scans where size matters more than anything else. For contracts, reports and forms, use Recommended or Strong.
- Expecting a text-only PDF to shrink a lot. A PDF that is mostly text is already compact, and the savings come mainly from photos. A small reduction, or a message that the file is already optimized, is normal here.
- Compressing a password-protected file. The tool can't read an encrypted PDF. Remove the password with Unlock PDF, compress, and protect it again if needed.
- Treating a smaller file as proof that sensitive content was removed. Compression re-encodes data; it never deletes or redacts anything.
- Not keeping the original. Re-saved photos can't be restored to their original quality, so keep the source PDF until you're sure the compressed copy is good enough.
FAQ
Will compressing make my text blurry or unselectable?
Not at the Recommended or Strong level. Those levels only re-save the photos embedded in the file and tighten the file structure; text, fonts and vector drawings are left exactly as they were, so text stays sharp, selectable and searchable. Only the Maximum level turns each page into an image, and the tool labels that trade-off before you choose it.
Why did my PDF barely shrink, or not download at all?
Most of a PDF's weight usually comes from photos and scans. A document that is mostly text is already small, so it can only lose a little. The tool never hands you a bigger file: if the compressed version isn't smaller than the original, nothing is downloaded and a message tells you the file is already well optimized.
Is there a file size limit for compression?
No limit is set by the site, because the file is processed in your browser instead of on a server. The practical ceiling is your device's memory: a scan with hundreds of high-resolution pages takes longer and can slow the tab down while its images are re-saved.
Does a smaller file mean private information was removed?
No. Compression changes how images and data are encoded; it never deletes, blurs or redacts content. Everything that was visible before compression is still in the file afterward.
Checklist before you send a compressed PDF
- Original file size noted before compressing
- Level chosen on purpose: Recommended or Strong for documents with text, Maximum only for scans
- Original PDF kept in case the compressed version isn't good enough
- Photos and small print checked at normal zoom against the original
- New file size checked against the limit that prompted the compression
- No assumption made that compression removed or hid sensitive content