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KDiff3
What it is
KDiff3 is a free, open-source desktop app for comparing and merging files and folders. It can compare two or three text files or folders, displaying differences at both line and character level. For merge work, it offers automatic merging and an editor for resolving conflicts, including three-way merges. Folder comparison and Git integration are supported. KDiff3 handles Unicode, UTF-8 and other file encodings; users can highlight or hide whitespace and comment changes, and print differences. It also supports version-control keyword and history merging, with network transparency through KIO. The app runs on Linux, macOS and Windows, and its listed license is GPL-2.0-or-later. The Free plan costs nothing, and there is no free trial. Linux installation options include Discover or another AppStream store, a distribution package manager, or Flathub. The app page links to a handbook, forum and bug-reporting page. The latest release shown is version 1.12.5, dated 2026-07-20.
For and against
For
- Compares two or three files or folders.
- Includes automatic and three-way merging.
- Supports Unicode and other encodings.
- Git integration and folder comparison are supported.
- Free and open-source under GPL-2.0-or-later.
Against
- No free trial is listed.
- Syntax highlighting is not supported.
The verdict
KDiff3 covers file and folder comparison alongside merge-conflict resolution and version-control features. It is free to use, with desktop support across three listed operating systems.
Who it suits
KDiff3 suits people comparing or merging files and folders on Linux, macOS or Windows. Its three-way merge and conflict-resolution tools may be useful for version-control work.
Plans and prices
Free open-source KDiff3
Desktop file and folder comparison and merging · GPL-2.0-or-later
Read 15 Oct 2026 · flathub.org
Free
Free and open-source software · GPL-2.0-or-later
Read 7 Oct 2026 · apps.kde.org
On the record
- AlternativeTo criticism
- AlternativeTo user comparisons describe KDiff3 as less lightweight than Meld and focused on a narrower desktop workflow than broader alternatives.alternativeto.net · read 15 Oct 2026
- AlternativeTo listing
- AlternativeTo categorizes KDiff3 as a free, open-source diff tool and shows 118 community likes.alternativeto.net · read 15 Oct 2026
- Automatic merging
- KDiff3 includes an automatic merge function.apps.kde.org · read 15 Oct 2026
- Build requirements
- The current build instructions require Qt 6.7 or newer, KDE Frameworks 6.2 or newer, CMake 3.22 or newer, ECM 6.2 or newer, Boost 1.71 or newer and a C++17-capable compiler.github.com · read 15 Oct 2026
- Command-line interface
- The project documents command-line syntax for two-way and three-way comparisons and output-file merges.github.com · read 15 Oct 2026
- Comparison
- It compares two or three text files or folders and shows differences line by line and character by character.apps.kde.org · read 7 Oct 2026
- Conflict editor
- An integrated editor lets users resolve merge conflicts interactively.docs.kde.org · read 15 Oct 2026
- Current release
- The KDE application page lists version 1.12.5 released on 2026-07-20.apps.kde.org · read 15 Oct 2026
- Documentation depth
- The official handbook covers file and folder workflows, command-line options, editing, printing, configuration, preprocessors, KIO networking, Git usage, troubleshooting questions and licensing.docs.kde.org · read 15 Oct 2026
- Encoding support
- KDiff3 supports Unicode, UTF-8 and other file encodings.apps.kde.org · read 15 Oct 2026
- Flathub usage
- Flathub reports approximately 543 downloads per month for KDiff3.flathub.org · read 15 Oct 2026
- Flatpak availability
- Flathub offers KDiff3 as a free desktop-only Flatpak for x86_64 and aarch64 architectures.flathub.org · read 15 Oct 2026
- Folder merge
- The handbook documents comparing and merging two or three folders, including per-file operations.docs.kde.org · read 15 Oct 2026
- Git integration
- The documentation includes instructions for using KDiff3 as Git's diff and merge tool.docs.kde.org · read 15 Oct 2026
- Help and support
- The app page links to the KDiff3 Handbook, a forum, and a bug-reporting page.apps.kde.org · read 7 Oct 2026
- License
- KDiff3 is distributed under the GNU GPL version 2 or any later version, identified on the product page as GPL-2.0-or-later.apps.kde.org · read 15 Oct 2026
- Limit: large binary files
- A SourceForge reviewer reports that large binary files are loaded entirely into memory, causing the program to become unresponsive.sourceforge.net · read 15 Oct 2026
- Limit: missing convenience features
- Reviewers request file-list search, summary statistics, direct text input, patch creation and printable difference reports.sourceforge.net · read 15 Oct 2026
