Altova DiffDog vs SourceGear DiffMerge

Altova DiffDog has no write-up on Specifiction yet; its figures are above.

SourceGear DiffMerge is a free desktop application for visually comparing and merging files and folders on Linux, macOS, and Windows. Its Diff feature displays changes between two files, highlights differences within lines, and supports editing. Merge compares three files and can combine changes automatically when it considers that safe. Folder Diff compares two folders side by side and classifies files as identical, equivalent, different, or present in only one folder. Rulesets and options let users adjust its appearance and behavior, and it can import files in a wide range of character encodings. A command-line interface compares files and can write differences in unified or traditional formats. The manual documents integrations with Git, Mercurial, TortoiseSVN, Microsoft TFS, and Microsoft VSS 2005. Windows Explorer integration adds context-menu actions for selected files or folders. The download page lists version 4.2 builds for Windows, MacOS 10.6+, Ubuntu 12.04+, and Fedora 17+. SourceGear support stated in February 2026 that it was no longer accepting registrations and was moving DiffMerge toward an open-source project.