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PDF Collation
Designed for on-device processing

Merge PDF Files Online

Combine 2 to 20 PDF documents into a single cohesive document. Reorder files before merging. Pages are copied into one output document in browser memory.

Select 2 to 20 PDF files to combine

Drag and drop multiple files or browse. 100% in-browser processing.

.PDF files only (Max 100MB batch)

Technical Notes & Guardrails

  • Supports between 2 and 20 PDF files per merge operation.
  • Aggregate total size limit: 100MB across all selected files.
  • Encrypted / password-protected PDFs are not supported.

How to Use the Merge PDF

Simple 3-step browser-local conversion workflow.

1Step 1

Select PDF Documents

Choose 2 to 20 PDF files (up to 100MB aggregate) from your device.

2Step 2

Arrange File Order

Drag and drop cards or use move buttons to arrange the exact document order.

3Step 3

Merge & Download

Pages are copied sequentially into a single PDF in memory. Click Download to save.

PDF Merging Technical Architecture

Technical characteristics and format differences.

Source Format

Multiple PDF Documents

Individual PDF files each containing separate page trees and resources.

  • 2 to 20 distinct PDF files
  • Individual metadata and page numbering
  • Separate document objects
Target Output

Merged PDF Document

A single unified PDF document containing all pages in the user-selected order.

  • Unified sequential page catalog
  • Preserved page content streams
  • Single downloadable file

Conversion Trade-Offs & Behavior

Pages are copied from the selected PDF files into one output PDF in the user-selected order. Processing occurs in-memory without server transmission.

Technical Specifications & Guardrails

On-Device Safe
File Count Range
2 to 20 PDF files
Aggregate Size Limit
100MB total across all files
Ordering Control
User-defined custom sequence
Engine
@cantoo/pdf-lib (In-memory page copying)
Processing Model
100% Client-Side
Frequently Asked Questions

Merge PDF FAQs

Answers to common technical questions and format capabilities.

How many PDF files can I merge at once?

You can merge between 2 and 20 PDF files in a single operation, with a combined aggregate file size of up to 100MB.

Does changing the file order change the final PDF?

Yes. The output PDF concatenates pages in the exact top-to-bottom order displayed in your merge queue.

Are my original PDF files modified or overwritten?

No. Your original files remain completely untouched on your device. The tool generates a brand-new merged PDF document in browser memory.

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