Diff Checker
Line-level text diff with inline and side-by-side views.
Enter text in both panels to compare.
Diff Checker compares two text blocks in your browser with inline or side-by-side views. Added and removed lines use prefixes, borders, and strikethrough—not color alone—and the diff engine loads dynamically for better performance.
How it works
Paste original and modified text. The tool debounces input, dynamically imports diffLines, and renders line-level changes. Inline mode shows unified +/- rows; side-by-side mode aligns removals and additions in a two-column table.
Benefits
- Line-level diffs with lazy-loaded engine
- Inline and side-by-side viewing modes
- Accessible labels via prefix, border, and strikethrough
- Live summary of added and removed line counts
- Copy and download unified diff output
Use cases
- Review config changes before applying them
- Compare API response snapshots during debugging
- Check copy updates between marketing drafts
- Verify script output after a refactor
Best practices
- Normalize line endings when comparing cross-platform files
- Use side-by-side mode for wide lines or parallel edits
- Clear panels before pasting secrets on shared machines
- Re-run Diff after trimming accidental trailing whitespace
Common mistakes
- Comparing files with different newline styles without normalizing
- Expecting word-level highlights from a line-based diff
- Pasting only one side and wondering why nothing changed
- Ignoring blank-line differences that still count as changes
Privacy
All diff computation happens locally in your browser. ToolHub does not receive your text. Optional device history stores both panels only if you explicitly enable and save entries on this machine.
Frequently asked questions
- Does the Diff Checker upload my text?
- No. Comparison runs entirely in your browser using the diff library loaded on demand.
- What diff algorithm is used?
- Line-level diffs via diffLines from the diff package, which is dynamically imported when you compare text.
- Can I view changes inline or side by side?
- Yes. Toggle Inline for unified +/- lines or Side by side for a two-column table aligned by change hunks.
- How are additions and removals labeled accessibly?
- Added lines use a plus prefix, left border, and aria-label. Removed lines add strikethrough and a minus prefix—not color alone.
- How do examples with two panels work?
- Example buttons load both sides at once. Internally the sample stores original and modified text separated by a --- divider line.
- Is large text supported?
- Diffing is debounced and runs locally. Very large inputs may take longer, but nothing is uploaded to a server.
- Can I copy or download the diff?
- Yes. Copy grabs a unified +/- text representation. Download saves the same output as a .diff file.
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