Why compress PDF files?
Gmail caps attachments at 25 MB. Outlook on the web is 20 MB. A 47-page scan of a signed lease can blow past both before you've attached the second page. Compression gets the file under the limit without you having to delete pages or split it.
Three things usually make a PDF bloated: embedded images (especially 600 DPI scans that nobody needs at 600 DPI), unused fonts that got embedded 'just in case', and metadata nobody reads. A good compressor targets all three.
How to compress a PDF for free
Three clicks, no signup:
- 1Open the Compress PDF tool and drop your file in.
- 2Pick a level: Low (smallest quality hit), Medium (balanced), or High (smallest file).
- 3Hit 'Compress PDF'. The new file downloads the moment it's done — everything happens in your browser, nothing leaves your machine.
What affects PDF compression?
Image-heavy PDFs compress the most. A scanned document with 300 DPI photos can often shrink 50–70% — there's just a lot of redundant pixel data to throw away.
Text-only PDFs are a different story. Text in a PDF is already vector data, encoded efficiently, so you might only see 10–20% off the top.
Embedded fonts, metadata, and orphaned objects are free wins — stripping them is lossless and saves another 5–15%.
Privacy-first compression
Here's the part most 'free PDF compressor' sites gloss over: every one of them uploads your file to a server, processes it there, and lets you download the result. Even if they delete it 60 minutes later, your document sat on their hardware for an hour. Backups, logs, employee access — all possible during that window.
PrivacyScanPDF runs the whole thing as JavaScript in your browser. The file never leaves your device. For contracts, medical records, or anything with a bank account number on it, that's the only acceptable setup.