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📄 PDFMerger - Free, Offline, Cross-platform PDF Merging Tool

A concise, free, cross-platform PDF merging tool that supports retaining the original bookmark directory structure and automatically generates file names as first-level directories. It features no ads, no pop-ups, and no watermarks, designed specifically for efficient office work and trusted computing environments.

🚀 ​​No installation required, ready to use after decompression
👉 Download Now (GitHub Releases)
👉 Domestic Mirror Download (Gitee Releases)

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✨ Key Features

• Multi-file Merging​​: Supports merging any number of PDF files into one.
• ​Mixed Merging of PDFs and Images​​: Supports merging any number of PDF files and images into a single PDF output.
• Bookmark Retention and Enhancement​​:
  • Take the ​​source file name​​ as the first-level bookmark directory
  • If the source file already has bookmarks, retain the bookmark hierarchy after merging and automatically downgrade them to child nodes (for quick positioning).
• Metadata Configuration​​: Customizable author, title, subject and other information of the output file.
• ​Smart Duplicate File Filtering/Allowance​​: Option to ignore duplicate added files or allow duplicate files.
• Real-time Progress Feedback​​: The graphical interface displays the merging progress.
• ​Cross-platform Support​​: Windows, macOS (Intel + Apple Silicon), Linux (x64 + ARM64).
• Fully Offline Operation​​: No internet connection is required. All document processing is performed locally; no documents are uploaded,ensuring privacy and security. (Users need to connect to the internet when actively clicking to upgrade the software on the About form, but no user data will be transmitted.)
• Clean and Distraction-free​​: No ads, no membership, no usage restrictions.
• Support merging of ultra-large PDF files​​: Tests have been completed for merging three files of 13GB each with 40,342 pages, outputting a 40GB document with 121,026 pages.
• Starting from v2.0, support for encrypted PDF files in the merging process will be available.
• Multilingual support: Chinese, English, Japanese, German, etc.

🖥️ System Requirements

• Operating System​​:

  • Windows 10 / 11
  • macOS 10.15+ (Intel / Apple Silicon)
  • Linux (Ubuntu 20.04+, UnionTech UOS, Kylin KOS, etc.)

• CPU Architecture​​: x64, ARM64

  • No .NET runtime installation required (self-contained version)

🚀 Usage Instructions

Graphical User Interface (GUI)

Multilingual support: Chinese, English, Japanese, German, etc.

1. Download the compressed package corresponding to your platform, and run the PDFMerger executable file after decompression.
2. Main Interface:
   • Click ​​"Add Files"​​ or directly drag PDF/IMG files into the window.
   • Supports multiple selection and repeated addition.
   • Adjustable file order (move up/down).
   • The output path is automatically generated by default, and can also be manually selected.
3. Click ​​"Start Merging"​​, and the progress bar will display in real time.
4. After the merging is completed, you can open the folder where the output file is located. Note: For ultra-large PDF files, when the interface indicates that the merge is complete but the Cancel Merge button is still clickable, the output file may not have finished being written to the disk. Please wait patiently for the output file to be fully saved to the disk.

📦 Download and Installation

Pre-compiled Packages

• Go to the Releases page to download the compressed package suitable for your system:

  • PDFMerger.1.0.0.win-x64.zip – Windows 64-bit
  • PDFMerger.1.0.0.win-x64-bundled.zip – Windows 64-bit self-contained runtime version
  • PDFMerger.1.0.0.macos-x64.app.tar.gz – macOS Intel
  • PDFMerger.1.0.0.macos-arm64.app.tar.gz – macOS Apple Silicon
  • PDFMerger.1.0.0.linux-x64.tar.gz – Linux 64-bit
  • PDFMerger.1.0.0.linux-x64-bundled.tar.gz – Linux 64-bit self-contained runtime version
  • PDFMerger.1.0.0.linux-arm64.tar.gz – Linux ARM64 (trusted computing devices)
  • PDFMerger.1.0.0.linux-arm64-bundled.tar.gz – Linux ARM64 (trusted computing devices) self-contained runtime version

• After decompression, double-click PDFMerger to run directly (Linux/macOS may require granting execution permissions).

🛠️ Developer Guide

Environment Requirements

• .NET SDK 8.0 or higher version
• Avalonia UI Framework
• Build using the project's PowerShell scripts and WSL virtual machine shell scripts

🤝 Contribution

• Issues and Pull Requests are welcome.
• When reporting bugs, please attach system information and reproduction steps.
• For new feature requests or improvements, please open an Issue for discussion first.

📄 License

• This project is licensed under the MIT License, which allows free use, modification, and distribution, including commercial use.

🧩 Tech Stack

• Avalonia UI – Cross-platform .NET GUI Framework

• PDFsharp – PDF Processing Core

• .NET 8 – Runtime and SDK

❓ FAQ

Q: The PDF directory bookmarks cannot be displayed in Chrome or Edge browsers after merging?

A: Some browsers may not support PDF bookmarks. Please use professional readers such as Adobe Acrobat Reader or PDF Expert to view.

Q: Can encrypted PDFs be merged?

A: Currently, encrypted PDFs are not supported. A password input function may be added in the future.

Q: Does the software require internet connection?

A: It is fully offline, requires no internet connection, and will not upload any files.

Q: Why can't my Apple Silicon Mac run the software?

A: Please download the -osx-arm64 version to ensure you are using the package matching the corresponding architecture.

📧 Contact

For business cooperation or customization requirements, please contact us via GitHub Issues.

🛡️ Note：

• Usage of the macOS version software

  • The macOS version of the program is not digitally signed. If you downloaded the tar.gz package from the GitHub Release, after extraction, macOS will automatically add an extended attribute named com.apple.quarantine to the file, which is the "unknown origin" tag.

  • When you try to run an application with this tag, Gatekeeper will perform stricter security checks.

  • For applications that have not passed Apple Notarization, the system will pop up a prompt saying "is damaged and can't be opened".

  • This issue is essentially "false damage" caused by the security mechanism, not that the file is actually broken.

  • You can remove the quarantine attribute by using the xattr command in the terminal for a single .app file to remove this attribute.

xattr -d com.apple.quarantine /path/to/PDFMerger.app

• Support for Image Files
  • Supported image file formats include common formats such as JPEG, PNG, BMP, GIF, TIFF, and WEBP.
  • If you encounter an unrecognizable image file, please ensure the file format is correct and try opening it with another image viewer to confirm its validity.
  • TIFF files decodable by the current ImageSharp TIFF decoder are supported; specially encoded TIFF files may not be recognized.
  • For files in formats such as tif, gif, and webp, if they contain multiple frames, each frame will be added to the PDF file as an independent page. If you only need one page, please process the image in advance.