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Last updated: April 8, 2026

Quick Answer: Yes, you can absolutely use Qt for free under its open-source licenses, primarily the GNU General Public License (GPL) and the GNU Lesser General Public License (LGPL). These licenses allow for free use, modification, and distribution of Qt for many applications, including commercial ones, as long as specific conditions are met.

Key Facts

Qt is available under the open-source GPL and LGPL licenses, enabling free use.
Commercial use is permitted under these open-source licenses, provided compliance with license terms.
The LGPL is often preferred for dynamic linking, offering more flexibility for proprietary applications.
For certain commercial scenarios, or to avoid open-source license obligations, a commercial license is available.
Qt's extensive libraries and tools are accessible without charge for developers adhering to open-source terms.

Overview

Qt is a powerful and widely-used cross-platform application development framework that provides a comprehensive set of tools and libraries for creating graphical user interfaces (GUIs), as well as non-GUI applications, for desktop, mobile, and embedded systems. Developed by The Qt Company, it's renowned for its C++ based language bindings, extensive module system, and its ability to deploy applications on various operating systems such as Windows, macOS, Linux, Android, iOS, and more, without requiring significant code rewrites. This cross-platform capability is a cornerstone of Qt's appeal, allowing developers to write code once and deploy it everywhere.

The question of whether Qt can be used for free is a common one, and the answer is a resounding yes, thanks to its dual-licensing model. Qt is available under both open-source licenses and commercial licenses. For the vast majority of developers and projects, the open-source options provide everything needed to build sophisticated applications without any licensing fees. This accessibility has fostered a large and active community, contributing to Qt's robust ecosystem and continuous evolution.

How It Works

Open-Source Licenses: Qt is primarily distributed under the terms of the GNU General Public License (GPL), version 3, and the GNU Lesser General Public License (LGPL), version 3. The LGPL is particularly popular as it allows for the use of Qt libraries in applications that are not themselves open-source, provided that the Qt libraries are dynamically linked. This offers a great deal of flexibility for commercial software development. The GPL, on the other hand, requires that any derivative work also be licensed under the GPL.
Commercial License: For those who wish to avoid the obligations of the GPL or LGPL, or for specific use cases that don't fit neatly within the open-source terms, The Qt Company offers commercial licenses. These licenses provide the same Qt framework but come with different terms and support options, and they require a purchase. They are often chosen by companies that need dedicated support, assurance against patent issues, or when developing proprietary software where linking with LGPL-licensed libraries might be a concern.
Key Modules and Tools: The free version of Qt includes access to its core modules, such as Qt Widgets for traditional desktop UIs, Qt Quick for modern, fluid UIs, Qt Network for internet connectivity, Qt SQL for database access, and many more. It also includes development tools like Qt Creator, a cross-platform integrated development environment (IDE) that greatly simplifies the development process. These tools and modules are all available under the open-source licenses.
Compliance: When using Qt under the GPL or LGPL, it's crucial to understand and comply with the license terms. For LGPL, this typically involves making the source code of your application available to users if you dynamically link to the Qt libraries, or at least providing a way for them to re-link your application with modified versions of the Qt libraries. For GPL, any modifications or derivative works of Qt itself, or applications that statically link to Qt, must also be made available under the GPL. Ignorance of these terms can lead to legal issues.

Key Comparisons

Feature	Qt Open Source (GPL/LGPL)	Qt Commercial License
Cost	Free	Paid
License Obligations	Must comply with GPL/LGPL terms (e.g., source code availability for GPL, dynamic linking requirements for LGPL)	No GPL/LGPL obligations; defined by commercial agreement
Source Code Access	Full source code available	Full source code available
Development Tools (Qt Creator)	Included	Included
Support	Community-driven support, forums, documentation	Official, dedicated support from The Qt Company, potentially faster bug fixes and expert assistance
Use in Proprietary Software	Possible with LGPL (dynamic linking)	Fully unrestricted
Use in Open-Source Software	Fully compatible (GPL requires open-sourcing derivative works)	Fully compatible

Why It Matters

Accessibility for Startups and Indies: The availability of Qt under open-source licenses significantly lowers the barrier to entry for individual developers, small startups, and open-source projects. This allows them to leverage a powerful, professional-grade framework without a substantial upfront investment, enabling innovation and competition. Many successful applications have been built using the free version of Qt.
Cross-Platform Reach: Qt's robust cross-platform capabilities, freely accessible through its open-source licenses, mean that developers can create applications that run on a wide array of devices and operating systems from a single codebase. This drastically reduces development time and cost compared to native development for each platform, making it a highly efficient choice for reaching a broad audience.
Community and Ecosystem Growth: The permissive nature of Qt's open-source licenses has fostered a vibrant and active global community. This community contributes to bug fixes, develops plugins, shares knowledge through forums and tutorials, and drives the evolution of Qt. This collaborative environment ensures that Qt remains a competitive and relevant framework, with a wealth of readily available resources for developers.
Flexibility in Licensing: The dual-licensing approach provides a crucial level of flexibility. Developers can choose the open-source path if their project aligns with the GPL or LGPL requirements, enjoying the benefits of free software. Conversely, businesses with specific proprietary needs or those seeking direct commercial support can opt for the commercial license, ensuring their business objectives are met without compromising on their software strategy.

In conclusion, for the vast majority of use cases, Qt is indeed free to use. Developers need only to be mindful of the specific terms of the GNU General Public License (GPL) or the GNU Lesser General Public License (LGPL) if they choose the open-source route. This open approach has cemented Qt's position as a leading choice for cross-platform development, empowering developers worldwide to create exceptional applications.