Diff Viewer

Paste two versions of text to instantly see additions, deletions, and modifications highlighted side by side. Switch between line-level and word-level diff modes. Great for reviewing code changes, config updates, or document revisions.

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About Diff Viewer

## What is a Diff?

A **diff** (short for "difference") shows the changes between two versions of text. It's foundational to version control systems like Git, where every commit is stored as a diff against the previous state.

### Diff modes

- **Line diff** — compares whole lines; a changed line shows as deleted + added

- **Word diff** — highlights individual changed words within a line for finer granularity

- **Unified diff** — combines both versions with `+` / `-` prefixes (the `git diff` format)

### When to use this tool

- **Code reviews** — compare before/after versions of a function or config

- **Debugging** — spot unintended changes between environments (staging vs. production configs)

- **Content editing** — review revisions to documentation or copy

- **Migration validation** — verify that transformed data matches expectations

### Related concepts

- **Three-way merge** — compares two branches against a common ancestor

- **Semantic diff** — understands code structure (AST-level), not just text

- **Patch files** — portable diff output that can be applied with `git apply`

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