Compress PDF Files Online
Reduce PDF file size without sacrificing quality. Shrink large PDFs for email, web upload, and archiving — free, private, and in your browser.
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Maximum file size: 10MB
Large PDF files are a daily frustration — they bounce back from email because they exceed attachment limits, they take forever to upload to cloud storage or portals, and they clog up shared drives. Dokfo's free PDF compressor solves this by intelligently reducing file size, typically by 30-80%, while keeping the document readable and professional. Most PDF bloat comes from embedded images scanned at higher resolutions than needed. A 300 DPI scan of a tax return produces a 40 MB file when 150 DPI would look identical on screen at only 6 MB. Dokfo's compressor detects and re-encodes these images at optimal resolution, strips redundant metadata, deduplicates embedded fonts, and rebuilds the PDF structure — all while preserving the visual appearance at your selected quality level. Three compression presets cover every scenario: "Maximum Compression" for quickly emailing large scans, "Recommended" for everyday use with a careful balance, and "High Quality" for print-ready documents where visual fidelity matters most.
How to Compress a PDF — Step by Step
1
Upload your PDF by dragging it onto the page or clicking the upload area. Dokfo reads the file locally and displays its original size.
2
Pick a compression level: Maximum for smallest size, Recommended for balanced quality, or High Quality for print-ready output. Each preset tunes image resampling, color profiles, and stream compression differently.
3
Click "Compress PDF" — Dokfo processes the file in your browser, shows the size reduction percentage, and downloads the optimized PDF automatically.
Why Compress PDFs With Dokfo?
Dramatic Size Reduction
Typical scanned documents shrink by 60-80%, and image-heavy reports by 30-50%. Text-only PDFs may already be small, but can still be optimized 10-20% by stream compression and metadata stripping.
Three Quality Levels
Choose exactly how aggressive the compression should be. Archive old receipts at maximum compression, compress client reports at recommended quality, and send print-ready brochures at high quality.
Fully Private — No Uploads
Your PDF never leaves your device. Compression runs entirely with WebAssembly in your browser, so confidential contracts, medical records, and financial statements stay on your computer.
No Watermarks, No Limits
Dokfo never adds watermarks or branding to compressed files. There is no file-size upper limit beyond what your device can handle, and no daily download caps on the compression quality.
When to Compress a PDF
- Reduce file size so attachments fit within Gmail, Outlook, or iCloud Mail limits (usually 20-25 MB).
- Speed up uploads to government portals, loan applications, visa forms, and job-application sites that often cap uploads at 5-10 MB.
- Save storage space on Google Drive, Dropbox, OneDrive, and personal archives when dealing with thousands of scanned documents.
- Accelerate loading for PDFs embedded in websites, online courses, and learning management systems — smaller files mean faster student access.
- Prepare documents for mobile viewing where download speed and data consumption matter.
Compression Happens on Your Device
Dokfo's compressor uses WebAssembly (compiled from Ghostscript and MuPDF) running inside your browser tab. The PDF is never transmitted to any server. Because compression is 100% local, there is no risk of a data breach, no third-party cloud involvement, and no storage of your content on our side. Open your browser's Network tab while compressing — you will see zero outbound traffic related to the file.
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Frequently Asked Questions About PDF Compression
Does compression reduce the readability or quality of my PDF?
It depends on the preset. "High Quality" preserves virtually all detail and is visually indistinguishable from the original. "Recommended" is optimized for screen viewing — tiny differences in image sharpness are possible but rarely noticeable. "Maximum Compression" is meant for quick sharing; fine image detail may be softened, but text remains fully readable.
How much can I expect my file size to decrease?
Scanned image-heavy PDFs typically shrink 60-80%. Reports with embedded photos and charts drop 30-50%. Text-only PDFs (like e-books) usually decrease 10-20% because they are already efficient. The reduction percentage appears on screen after compression completes.
Does compression remove text searchability?
No. Selectable, searchable text is preserved in all compression modes. If your PDF was already searchable (e.g., exported from Word or run through OCR), it will remain searchable after compression.
Are my files uploaded to your servers?
No. Dokfo processes everything locally in your browser using WebAssembly. Nothing is uploaded, stored, or transmitted. You can verify this in the browser's developer tools Network panel.
Can I compress very large PDFs (hundreds of MB)?
Yes, though very large files (500+ MB) may take longer and consume significant memory. For best performance, close other browser tabs and use a modern laptop or desktop rather than a low-end phone.
Does Dokfo add a watermark to compressed PDFs?
Never. Dokfo never adds watermarks, branding, or any visible mark to your output files — free or paid tier.
Can I compress password-protected PDFs?
You must unlock the PDF first using Dokfo's Unlock PDF tool (if you own the password). Encrypted streams cannot be recompressed until the encryption layer is removed.