PDF Merge (Combine PDF Files Online)
Combine multiple PDF files into one in seconds. 100% secure and local processing.
Drop PDF files here to merge
PDF Merge Use Cases
Frequently Asked Questions
Q. What's the maximum file size?
Each input PDF can be up to 2 GB; the total merged output has no hard limit beyond your device RAM.
Q. Does it preserve bookmarks and hyperlinks?
Yes. Bookmarks are merged into a hierarchy, and all internal/external hyperlinks are preserved.
Q. Can I merge password-protected PDFs?
Only after decryption. The tool detects encrypted files and prompts for the password client-side.
Q. Will the tool upload my files?
No. All merging happens in your browser using pdf-lib/WASM; files never leave your device.
Q. Does merging degrade image quality?
No recompression occurs by default—original images are byte-copied unless optimization is enabled.
📄 File Name Sorting Guide
The most common cause of scrambled merging order is the operating system's sorting method.
| Sorting Type | Example Result | Environment |
|---|---|---|
⚠️String Sort | 1.pdf, 10.pdf, 2.pdf, 20.pdf | Old Linux, Default JS sort() |
✅Natural Sort | 1.pdf, 2.pdf, 10.pdf, 20.pdf | Windows Explorer, macOS Finder |
🌐Locale Sort | Corrected international order | Browser Intl.Collator |
This tool uses Natural Sort by default. Using 0-padding like "ch1-part01.pdf" ensures the highest sorting stability.
🛠 Troubleshooting PDF Merge Failures
File Won't Open
Cause: One source is encrypted
Blank Pages
Cause: Corrupted OCR layer
Huge File Size
Cause: Duplicate font embedding
Broken Text
Cause: Missing subset fonts
App Freezes
Cause: 1,000+ pages / 100MB+ per file
Key Features
- Secure 100% browser-side merging
- No file count or size restrictions
- Lossless quality preservation
- Works on all devices including mobile
Our PDF Merge tool is designed to simplify office workflows by combining multiple documents into one. Process sensitive contracts and personal files safely without uploading to external servers.