What Is a Text Diff Tool?

A diff tool compares two pieces of text and highlights exactly what has changed between them — additions, deletions, and modifications. It's an essential tool for developers, writers, legal professionals, and anyone who works with versioned text.

Common Use Cases for Text Comparison

  • 👨‍💻 Code review — Compare old and new versions of a code file.
  • 📄 Document comparison — Find changes between contract revisions.
  • 🔧 Config file comparison — Spot differences between environment configs.
  • 📊 Data comparison — Compare CSV exports or JSON API responses.
  • ✍️ Content editing — Track editorial changes in articles and blog posts.

How to Use FavorTool Text Diff

  1. Open FavorTool Text Diff.
  2. Paste the original text in the left panel.
  3. Paste the modified text in the right panel.
  4. Differences are highlighted instantly:
    • 🟢 Green = Added content
    • 🔴 Red = Removed content
    • 🟡 Yellow = Modified lines
  5. Use the stats panel to see total changes at a glance.

Diff Algorithms Explained

The most common diff algorithm is the Myers diff algorithm, which finds the shortest edit script (minimum number of insertions and deletions to transform text A into text B). Tools like Git use this algorithm under the hood.

Tips for Better Diffs

  • Normalize whitespace/indentation before diffing to focus on meaningful changes.
  • For JSON files, format both sides first using the JSON Formatter before comparing.
  • Sort keys alphabetically before diffing JSON objects.