PDF4QT
For Windows and Linux, PDF4QT offers an open-source editor and reader, rendering tools, desktop applications, command-line tools, and a C++ library.
About PDF4QT
PDF4QT is a PDF editor and reader for Windows and Linux. It ships as four desktop applications: Viewer Profi (document reading, encryption, signature verification, annotation editing, regular-expression text search, page-to-image conversion and plugins), Viewer Lite for essential viewing, DocPage Organizer for merging, splitting, moving, cloning and adding pages, and DocDiff for comparing two documents and exporting the differences to XML. Developers can use a C++ library and a command line tool for script integration.
The project states it is open source, hosted on GitHub under the LGPLv3 license, with licensing terms intended to suit commercial as well as open-source users. Stated goals include full PDF 2.0 integration, which the developer describes as a work in progress, and support for high-DPI 4K/8K monitors. No pricing information is given on the homepage.
Key features
- Viewer Profi: encryption, digital signature verification, annotation editing, regex text search
- DocPage Organizer merges, splits, moves, clones or adds pages
- DocDiff compares two documents and exports differences to XML
- Command line tool and C++ library for scripting and development
- Hardware-accelerated rendering, multithreading and color management
- Text-to-speech and audio book conversion from PDFs
Best for: Windows and Linux users who want a free, source-available PDF reader and editor, and developers who need a C++ library or command line tool for PDF work.
Good for
- Open source under LGPLv3, with licensing described as more flexible than GPL or AGPL for commercial users
- Combines four desktop applications with a developer library and command line tool
- Covers editing, annotation, comparison, encryption and signature verification in one suite
Watch out for
- Full PDF 2.0 integration is described as a work in progress
- Applications are offered for Windows and Linux only
- The Lite viewer is limited to essential viewing functions
PDF4QT at a glance
- Website
- jakubmelka.github.io
- Category
- Online Tools › PDF & Document Tools
- Type
- Online tool
- Pricing
- Not confirmed. Check the site
- Platforms
- Linux, Web, Windows
- Open source
- Not stated
- Language
- English
- Last checked
- Oct 5, 2026 · Online when checked
- Listed
- Oct 5, 2026
Guides for PDF & Document Tools
PDF4QT alternatives
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An open-source toolkit for Windows and Linux, PDF4QT combines desktop apps, command-line tools, and a C++/Qt engine for PDF work.
Open source
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Turn web pages into PDF, EPUB, HTML, or Markdown documents with Percollate, a command-line tool.
Open source
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PDF4QT FAQ
Which platforms does PDF4QT support?
The applications are designed for Windows and Linux.
What license does PDF4QT use?
The project is hosted on GitHub and operates under the LGPLv3 license.
Is there anything for developers?
Yes. A C++ library and a command line tool are provided for script integration.
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