Compress PDF Online — Free & Fast
Reduce PDF file size while maintaining quality. Remove unnecessary data, optimize images, and compress efficiently — all in your browser.
Why Choose Our PDF Compressor?
True Privacy
Your PDF never leaves your computer. Cloud-based compressors upload your files to servers where they may be stored or scanned. LocalPDF keeps everything local.
Smart Compression
Removes redundant data, optimizes structure, and strips metadata without degrading content quality. Typical size reduction: 30-70%.
No Size Limits
Compress PDFs of any size. Online tools often cap uploads at 50-100 MB. Your browser's available memory is the only constraint here.
No Quality Degradation
Unlike aggressive server-side compression that ruins image quality, LocalPDF preserves readability and visual fidelity.
Instant Processing
No upload delays. Compression happens at native speed in your browser — usually under 3 seconds even for large files.
No Watermarks
Some free compressors add watermarks to output files. LocalPDF never modifies your content beyond compression.
Key Features
How It Works
100% Private Sandbox: Your files never leave your device. All processing happens locally in your browser's secure memory.
Frequently Asked Questions
How much smaller will my PDF become?
Typical reduction is 30-70% depending on the original file. PDFs with metadata, encryption, or redundant data compress more. Scanned documents with optimized images may see minimal reduction.
Will compression affect PDF quality or readability?
No! Our compression removes redundant data and metadata without touching page content. Text remains sharp, images keep their resolution. We do not downsample images or reduce quality like aggressive server-side compressors.
Can I compress password-protected PDFs?
Our compression automatically removes encryption and passwords as part of the optimization process. If you need to re-protect the compressed PDF, use our Protect PDF tool afterward.
Why does my PDF barely get smaller?
If your PDF is already optimized (e.g., created by modern software or previously compressed), there's less redundant data to remove. Scanned documents or PDFs with minimal metadata won't compress much.
What data gets removed during compression?
We remove:
- Encryption and password protection
- Document metadata (author, creation date, keywords)
- Hidden embedded data
- Redundant structural elements
Can I compress multiple PDFs at once?
Yes! You can batch-compress multiple files. Upload all PDFs at once, and each will be compressed individually. You'll download them one by one or as a ZIP archive.
Is there a file size limit for compression?
No limits during beta! You can compress PDFs of any size. Processing happens in your browser, so your device's available memory is the only constraint. Most devices handle 100+ MB PDFs easily.
Are my files uploaded to a server?
Never! All compression happens 100% locally in your browser using JavaScript. Your PDF never leaves your device - complete privacy guaranteed.
Technical Architecture: How it Works
Zero-Knowledge Architecture
Our system is designed so that your data is never seen by anyone else. Processing happens in the browser's secure memory space.
WebAssembly Performance
We use high-performance WebAssembly modules to achieve desktop-grade PDF processing speeds directly in your web browser.