Free Online PDF Compressor - Reduce PDF Size Securely
Compress PDF files instantly without uploading to any server. Our browser-based PDF compressor reduces file size by converting pages to optimized images, making it perfect for email attachments, web uploads, and storage optimization. Unlike cloud-based tools, your documents never leave your device—everything is processed locally using JavaScript and WebAssembly for maximum privacy and security.
1When to use this tool?
2Features
- 100% client-side processing—files never leave your browser
- Three compression levels for quality vs. size balance
- Real-time progress indicator during compression
- Before/after file size comparison
- Works offline after initial page load
- No file size limits (depends on browser memory)
- No watermarks or branding added
- Compatible with all modern browsers (Chrome, Firefox, Safari, Edge)
3How to Use
- Drag and drop your PDF file or click to browse and select.
- Choose your preferred compression level: Low (better quality), Medium (balanced), or High (smaller size).
- Click the 'Compress PDF' button to start processing.
- Wait for compression to complete—progress is shown in real-time.
- Preview the size reduction and download your compressed PDF.
FAQ
Q. How does browser-based PDF compression work?
A. Our tool uses PDF.js to render each page as a canvas image, then recompresses it as JPEG with your chosen quality setting. The compressed images are assembled into a new PDF using pdf-lib. All processing happens in your browser's memory using JavaScript—no server uploads required.
Q. Is my PDF data safe with this tool?
A. Absolutely. Your files are processed entirely on your device and are never uploaded to any server. Once you close the browser tab, all data is cleared from memory. This makes our tool ideal for sensitive documents like contracts, medical records, or financial statements.
Q. Why does compression make text unselectable?
A. To achieve maximum compression, pages are rasterized (converted to images). This removes the underlying text layer, making text unselectable and unsearchable. If you need searchable text, consider using OCR tools after compression.
Q. What is the maximum file size I can compress?
A. There's no hard limit—it depends on your device's available memory. Most modern devices can handle PDFs up to 100MB+. For very large files, enable High Performance mode which removes the 50MB safety limit.
Q. Can I compress password-protected PDFs?
A. Yes, but you'll need to unlock the PDF first using our Unlock PDF tool. Once unlocked, you can compress it normally.
Q. How much can I reduce my PDF file size?
A. Results vary depending on the original content. PDFs with lots of images typically see 50-80% size reduction. Text-heavy documents may see less reduction. Use Medium compression for a good balance between quality and size.