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Compress PDF online
Cut PDF size for email, upload, or archiving. Runs entirely in your browser, so your files never touch our servers.
Compress PDF reduces the file size of a PDF by re-encoding images and streams while preserving readable quality. DocTools runs the entire compression in your browser, so the file never uploads to a server. Use Compress PDF to reduce file size without losing quality in seconds, straight from your browser.
- Free to use
- No signup
- No uploads
- Works offline
Why use Compress PDF
- 40-80% smaller for image-heavy PDFs
- Three quality profiles: balanced, small, or maximum
- Batch multiple PDFs in one pass
- Files never leave your device
Every step runs client-side in your browser via WebAssembly. No file, page, or byte is transmitted to DocTools or any third party.
How to use Compress PDF
- Choose your PDF Drag a PDF into the drop zone or click to browse. It stays on your device.
- Pick a compression level Select recommended, high compression, or maximum quality.
- Download the compressed PDF Save the smaller PDF straight from your browser.
Benefits
Fits inside email limits
Most inboxes cap attachments at 25 MB. Compression brings typical reports under the line in one click.
Faster uploads and downloads
Smaller PDFs move faster over slow connections and free up cloud storage.
Private by design
Compression runs locally in WebAssembly. No file, page, or metadata is ever transmitted.
Who it is for
Legal teams
Bundling exhibits into a court filing under the 35 MB e-filing cap Outcome: Ship the packet in a single upload with no quality complaints.
Students
Emailing a thesis draft with embedded figures Outcome: Attach directly instead of sharing a cloud link.
Design agencies
Sending client deliverables from a portfolio Outcome: Preserve print-ready appearance at a fraction of the size.
How it works
Compress PDF loads your PDF into memory, applies the change you requested to the underlying data rather than to a screenshot of it, and writes a fresh copy for download. Your original stays untouched on disk, and every step of Compress PDF happens inside your browser sandbox.
Frequently asked questions
Does the PDF get uploaded to your servers?
No. Compression runs entirely in your browser using WebAssembly. The file never leaves your device.
How much can I compress a PDF?
PDFs with large images typically shrink 40-80%. Text-only PDFs are already small and shrink less.
Will image quality drop?
You choose the compression profile. Higher compression re-encodes embedded images at a lower quality; text remains crisp.
Is there a file size limit?
The practical limit is your device's memory. Modern laptops handle PDFs up to a few hundred megabytes.
Does compression affect PDF/A conformance?
Aggressive image re-encoding can invalidate PDF/A. Use the balanced profile and re-validate if you need to preserve conformance.
Can I compress a password-protected PDF?
Unlock it first with the Unlock PDF tool, then compress. Encrypted streams cannot be re-encoded.
Related tools
- Compress Images in PDF | Reduce embedded image sizes
- Word Compressor | Reduce DOCX file size
- PPT Compressor | Reduce PPTX file size
Last updated: 2026-07-09