Merge PDF Files Securely: No Upload, 100% Client-Side
Combine multiple PDF files into one document — instantly and securely. All processing happens in your browser, ensuring complete privacy. No uploads, no registration, no hidden fees.
Why Choose Our PDF Merger?
100% Client-Side Processing
Unlike other online PDF mergers that upload your files to remote servers, LocalPDF processes everything locally in your browser. Your documents never leave your device, ensuring complete privacy and security.
Lightning-Fast Performance
No upload delays, no waiting in queues. Merging happens instantly because files stay on your computer. Average processing time: under 2 seconds.
No File Size Limits
Many online tools restrict file sizes to 10-50 MB. With LocalPDF, you can merge PDFs of any size — your browser is the only limit.
Zero Data Collection
We don't track you, store your files, or require accounts. No cookies, no analytics, no hidden terms. Just pure functionality.
Works Offline
Once loaded, the tool works without an internet connection. Perfect for sensitive documents you don't want transmitted over networks.
Preserve Quality
Lossless merging — your PDFs maintain original resolution, formatting, and metadata. No compression artifacts or degraded images.
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
What is Smart Merge and how does it work?
Smart Merge is our AI-powered feature that automatically analyzes your PDF documents and suggests optimal sorting options. It detects dates within documents, recognizes filename patterns (like part1, part2), identifies potential duplicates, and offers one-click sorting — all processed locally in your browser for complete privacy.
Can I merge password-protected PDFs?
Yes, but you'll need to provide the user password for each protected PDF before merging. The merged output won't be password-protected unless you use our Protect PDF tool afterward.
Is there a limit on the number of PDFs I can merge?
No limit during beta! You can merge as many PDF files as you want. The only constraint is your device's available memory. Most modern devices can handle merging dozens of PDFs without issues.
Will the merged PDF keep bookmarks and links?
Yes! Our merge tool preserves internal bookmarks, hyperlinks, and document metadata from all source PDFs. Bookmarks are combined in the order you arrange the files.
Does merging reduce PDF quality?
No quality loss! Merging is a lossless operation - all pages, images, fonts, and formatting are preserved exactly as they appear in the original files. No compression or downsampling occurs.
Can I change the order of PDFs before merging?
Absolutely! Before clicking 'Merge', you can drag and drop files to rearrange them in any order. You can also use Smart Merge to automatically sort by date, filename, or file size. Preview pages from each PDF to ensure correct ordering.
How does duplicate detection work?
Smart Merge analyzes the text content of your PDFs and compares file sizes to identify potential duplicates or very similar documents. When found, you'll see a warning with an option to keep only the first file from each duplicate group.
What happens if PDFs have different page sizes?
The merged PDF will preserve the original page size for each page. For example, if you merge an A4 document with a Letter-size document, the output will contain both page sizes in the final file.
How can I merge PDFs without compromising data security?
To merge PDFs securely, use a **client-side tool** like LocalPDF. The merging process is executed **locally in your browser's RAM** using WebAssembly, ensuring your files never leave your device. This **no-upload approach** provides superior data sovereignty compared to cloud-based alternatives.
Can I merge PDFs on mobile devices?
Yes! Our tool works on iOS (Safari), Android (Chrome), and all modern mobile browsers. The interface adapts to touchscreens for easy drag-and-drop file arrangement.
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.