Online PDF Merger
Merge multiple PDF files into one for free. Drag to reorder, secure local processing.
How to Use
Select file
Start process
Local processing
Download result
Complete PDF Merge Guide
Merge Features
Allin PDF's merge function executes entirely in your browser — selected PDF files are never uploaded to any server. The workflow is intuitive: select or drag-and-drop multiple PDF files into the tool area, reorder by dragging, then click merge to generate a single combined PDF. The merge preserves all source file properties — page dimensions, bookmarks, links, form fields are all maintained. Supports merging up to 20 files at once (50 for Pro), max 20MB per file (50MB Pro). Speed is exceptional: merging ten 10-page PDFs typically takes just 1-2 seconds.
Processing Results
Technical Specifications
Feature Comparison
| Feature | Allin PDF | Other Tools |
|---|---|---|
| File Count | Unlimited | Usually 2-20 limit |
| Reordering | Drag-and-drop | Some lack reordering |
| Metadata | Preserves bookmarks & TOC | Usually loses metadata |
Key Facts
PDF merge supports unlimited input files with drag-and-drop reordering.
Merging runs locally in the browser via WebAssembly — files never uploaded to any server.
Preserves bookmarks, table of contents, and page metadata from source files.
Privacy Protection
WebAssembly local processing means: files never leave your device, no network transfer, no server storage. Basic features work even offline.
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FAQ
How many PDFs can I merge at once?
There is no hard limit on the number of files. You can merge dozens of PDFs in a single operation. The practical limit depends on total file size — free users have a 5MB total limit, Pro users support up to 50MB combined.
Can I reorder pages before merging PDFs?
Yes. Allin PDF allows you to drag and drop files to rearrange their order before merging. You can preview each file and reorder them freely. The merged PDF will follow your specified order.
Is PDF merging done locally or on a server?
Completely local. PDF merging is processed in your browser using pdf-lib (WebAssembly). Files never leave your device and are never uploaded to any server. This ensures complete privacy for sensitive documents.
Do merged PDFs retain bookmarks and links?
The current web-based merge preserves page content including text, images, and vector graphics. However, interactive elements like bookmarks, form fields, and hyperlinks may not be retained during browser-based merging. For full metadata preservation, the desktop app offers more complete merging.
Process Documents Anywhere
Download the Allin PDF app for high-quality offline conversion