Compress PDF files

How to Compress PDF

1

Add your PDFs

Click “Select files” or drag and drop one or more PDFs. Batch compression is supported — all files use the same quality preset.

2

Choose a quality preset

Pick lossless (no quality change, modest size reduction), balanced (recommended for most documents), or maximum (smallest file, slight quality loss on images).

3

Compress and download

Click “Compress”. Each file processes in your browser. Download starts automatically when the batch finishes.

Every step runs in your browser. No server uploads, no waiting.

Why use this tool

DukPdf’s Compress PDF tool reduces the file size of your PDFs without re-rendering or stripping content. Choose a quality preset (lossless, balanced, or maximum) and the compression runs locally in your browser using qpdf. Your file is read, compressed, and saved without ever touching a server. If you need to combine several compressed files, use Merge PDF. To add a password to the compressed result, use Protect PDF. For a deeper guide covering lossy vs lossless compression, see our compress PDF guide.

When you'd use this

Email attachment limits

Shrink a PDF that’s too large for Gmail (25MB), Outlook (20MB), or a corporate mail server — without uploading the document anywhere.

Upload form size caps

Reduce a scanned PDF to fit a portal that caps uploads at 5MB or 10MB. Quality stays readable.

Archive storage

Cut long-term storage costs by compressing old reports, contracts, and tax documents before archiving.

Faster page loads

Compress product catalogs, manuals, and ebooks embedded in your website so they open quickly for visitors.

Why this matters for your privacy

☁️ CLOUD PDF TOOLS
📄 your-file.pdf
↓ uploaded over the internet
☁️ their server

A copy of your document sits on someone else’s infrastructure — deleted on their schedule, not yours.

✗ OUT OF YOUR HANDS
DukPdf
📄 your-file.pdf
⟳ stays right where it is
💻 your device

Processed by your own browser, start to finish — on your machine, under your control.

✓ STAYS ON YOUR DEVICE

We send the software to your file — not your file to our servers.

Compress PDF — questions

How much can I shrink a PDF?

Typically 20–60% for image-heavy PDFs, less for text-only documents. The actual reduction depends on the original content — scanned PDFs with large images compress most.

Will compression reduce image quality?

Lossless mode keeps images identical. Balanced and maximum modes downsample images slightly — readable on screen, fine for most print use. Choose lossless if you need pixel-perfect output.

Can I compress password-protected PDFs?

Yes. You’ll be prompted for the password before compression starts. The compressed file is saved without the password — add one with Protect PDF if needed.

Are my files uploaded during compression?

No. Compression runs entirely in your browser using qpdf compiled to WebAssembly. Open DevTools → Network tab — zero upload requests.

What’s the difference between lossy and lossless compression?

Lossless removes metadata, duplicates, and inefficient encoding without changing any pixel or character. Lossy also downsamples images and reduces font subsets — smaller files, but not byte-identical to the input.

Is there a file size limit?

No hard limit — the tool is constrained only by your device’s available memory. Files up to 500MB work on most modern browsers.

Tools that pair with compress pdf

→ Merge PDFCombine multiple compressed files→ Protect PDFPassword-protect after compressing→ Edit MetadataStrip authoring metadata to shrink further→ OCR PDFMake scanned PDFs searchable first→ Split PDFExtract and compress specific pages→ Remove PagesDrop pages to reduce size further
🔒 DukPdf — YOUR FILES NEVER LEAVE YOUR DEVICE

Ready to compress pdf? Your files stay yours.

No server uploads. No watermark. Just open a tool, drop your files, and download the result. Your original files are never modified.

↑ Back to upload