The diff viewer uses Monaco Editor — the same engine that powers VS Code — to show text differences side by side with both panels fully editable. Paste two versions of code, configuration, or any plain text and changes highlight instantly; edit either panel and the diff annotations update in real time without resubmitting.
What the Diff Output Looks Like
The tool compares content line by line using the longest common subsequence algorithm. Three annotation types appear:
- Deleted lines (red background): present on the left, absent on the right
- Added lines (green background): present on the right, absent on the left
- Unchanged lines (no background): identical on both sides
The toolbar shows total added and deleted line counts and provides previous/next diff navigation buttons. In large files this means you can jump directly between changes without manual scrolling.
Two Ways to Use the Editor
Compare two existing versions
- Paste each version into its respective panel
- Review highlighted differences line by line
- Useful for code review and document proofreading
Edit while comparing
- Paste the original on the left, then edit directly on the right
- Diff annotations show what you have changed so far
- Useful for resolving merge conflicts and consolidating two drafts
Syntax Highlighting
Over 100 programming languages are supported, including JavaScript/TypeScript, Python, HTML/CSS, JSON/YAML, SQL, and Markdown. Language can be switched manually from the toolbar; the default is plain text mode.
Windows vs Unix Line Endings
If every line turns red even though the content appears identical, the two sides likely have different line endings. Windows uses \r\n and Unix/macOS uses \n. Normalizing line endings before pasting resolves the issue. Differences that appear to be full-file changes but are actually just line-ending mismatches are the most common false positive in diff tools.