diff

WinMerge is an open source differencing and merging tool for Windows.

Beyond Compare is a multi-platform utility that combines directory compare and file compare functions in one package.

QNAP QuDedup Extract Tool helps restore deduplicated .qdff

Visual diff and merge tool

Freeware Visual File Comparison Tool

Excel file comparison tool

Diff/Patch Frontend

Advanced 2 and 3-way file comparison (diff), merging, and folder synchronization

Helix Visual Merge Tool (P4Merge) is a three-way merging and side-by-side file comparison tool. Use it to visualize your merges, obtain comprehensive file history, and compare a broad range of image files.

Intelligent document comparison tool

Difftastic is a structural diff tool that compares files based on their syntax.

A C\C++ library and command-line tools for Diff & Patch between binary files or directories(folder); cross-platform; runs fast; create small delta/differential; support large files and limit memory requires when diff & patch.

See all the changes in your documents, locally and offline. Take your work to the next level.

A syntax-highlighting pager for git, diff, and grep output

Cross-repository file synchronization through intelligent iterative merging

CLI search and replace

GNU Diffutils is a package of several programs related to finding differences between files.

KDiff3 is a diff and merge program.

JSON diff and patch.