Text Diff Checker
Compare two texts side by side online free. Instantly see every difference highlighted with the Myers diff algorithm.
| 1 | { |
| 2 | "name": "everytool", |
| 3 | "version": "1.0.0", |
| 4 | "description": "The ultimate collection of free online tools", |
| 5 | "author": "EveryTool Team", |
| 6 | "dependencies": { |
| 7 | "react": "^18.2.0", |
| 8 | "next": "14.1.0", |
| 9 | "lucide-react": "^0.344.0" |
| 10 | }, |
| 11 | "devDependencies": { |
| 12 | "typescript": "^5.0.0", |
| 13 | "tailwindcss": "^3.4.0" |
| 14 | } |
| 15 | } |
| 1 | |
| 2 | { |
| 3 | NaN "name": "everytool-pro", |
| 4 | NaN "version": "1.1.0", |
| 5 | NaN "description": "The ultimate collection of free online tools for developers", |
| 6 | "author": "EveryTool Team", |
| 7 | "license": "MIT", |
| 8 | "dependencies": { |
| 9 | "react": "^18.2.0", |
| 10 | "next": "14.2.0", |
| 11 | "lucide-react": "^0.360.0", |
| 12 | "framer-motion": "^11.0.0" |
| 13 | }, |
| 14 | "devDependencies": { |
| 15 | "typescript": "^5.3.0", |
| 16 | "tailwindcss": "^3.4.1", |
| 17 | "eslint": "^8.0.0" |
| 18 | } |
| 19 | } |
Whether you are a developer reviewing code changes, a writer comparing document versions, a DevOps engineer auditing config file updates, or an analyst spotting what changed between two data exports - comparing two pieces of text manually is slow, error-prone, and painful. This free online text diff checker does it instantly.
Paste your two texts and get a color-highlighted side-by-side comparison powered by the same Myers diff algorithm used in Git. Every added line, every removed line, and every changed word within a line is highlighted. See similarity scores, navigate between changes, compare JSON intelligently, merge changes selectively, and export the diff as a polished HTML report - all in your browser, completely free, with no data ever leaving your device.
How to Use the Text Diff Checker
- Paste your original text in the left panel (Version A) and your modified text in the right panel (Version B).
- The diff is computed instantly - deleted lines are highlighted red, added lines green.
- Within changed lines, word-level highlights show exactly which words changed.
- Use the Stats Bar to see how many lines were added, removed, or modified and the overall similarity percentage.
- Switch between Side by Side, Unified, and Inline views to find the layout that works best for your use case.
- Use Change Navigation (← →) to jump between change blocks without scrolling.
- Enable JSON mode in Comparison Options for cleaner JSON comparison.
- Export the result as a plain text diff or a styled HTML report.
Understanding the Diff Views
1Side by Side View
The classic view best for reviewing code changes. The original text is on the left and the modified text is on the right. Both sides scroll simultaneously, allowing you to easily track large structural changes. Empty spacer lines are added to keep unchanged blocks completely aligned.
2Unified View
Displays all changes combined in a single column in sequential order. Deleted lines are marked in red with a minus (-) and inserted lines are marked in green with a plus (+). Unchanged lines are grouped together, and long sequences of unchanged lines are collapsed to reduce noise, making it the best format for copying or sharing quickly.
3Inline View
A hyper-focused view showing only the changed sections. Each change block shows the before (red) and after (green) lines together, with unchanged sections completely collapsed. This is ideal for rapidly scanning through edits without having to scroll through large blocks of identical content.
What is the Myers Diff Algorithm?
The Myers diff algorithm, created by Eugene Myers in 1986, is the algorithm that powers Git, GNU diff, and virtually every modern diff tool. It finds the shortest edit script - the minimum insertions and deletions to transform one text into another. This produces the most natural, human-readable diff because it minimizes unnecessary changes. This tool implements the full Myers algorithm natively in the browser without any external libraries.
Common Use Cases
Key Features
- ✓ Myers diff algorithm - same as Git
- ✓ Side-by-side, unified, and inline views
- ✓ Word-level highlighting
- ✓ Real-time diff statistics and similarity %
- ✓ JSON comparison mode with normalization
- ✓ Ignore whitespace, case, and line endings
- ✓ Change navigation with keyboard shortcuts
- ✓ Change heatmap / minimap navigation
- ✓ Merge tool to accept changes from A or B
- ✓ Export to HTML report or .txt
- ✓ Share small texts via URL
- ✓ 100% free - no data sent to server
100% Free & 100% Private
All processing happens entirely in your browser. We never upload your data to any server. No signup, no account, no hidden fees. Just free, secure tools.
Frequently Asked Questions
How do I compare two texts online?
Paste your original text in the left panel and your modified text in the right panel. The diff is computed instantly and all differences are highlighted - deleted lines in red, added lines in green, with word-level highlights showing exactly which words changed within each line.
Can this tool compare JSON files?
Yes. Switch to JSON mode in the Comparison Options panel. The tool will normalize JSON formatting (pretty-print both sides) before computing the diff, so you see meaningful differences rather than formatting noise.
What is the Myers diff algorithm?
The Myers diff algorithm is the standard algorithm used in Git and most diff tools. It finds the shortest edit script - the minimum number of insertions and deletions needed to transform one text into another. This produces the most natural-looking diff that humans find easiest to read.
Can I ignore whitespace when comparing?
Yes. Open the Comparison Options panel and enable Ignore whitespace changes. This normalizes leading/trailing spaces and internal whitespace so only meaningful content differences are highlighted.
Can I export the diff result?
Yes. You can download the diff as a plain text unified diff file (.txt) or as a self-contained HTML report with color highlighting that works in any browser. You can also copy the unified diff to clipboard.
What is word-level diff highlighting?
Within lines that have changed, the tool runs a secondary diff on individual words to show exactly which words were added, removed, or modified. Deleted words are highlighted in darker red and inserted words in darker green, making it easy to spot small changes within long lines.
How is the similarity percentage calculated?
Similarity is calculated as the ratio of matching characters to total characters in both texts: 2 × equal characters ÷ (total chars in A + total chars in B) × 100. Two identical texts score 100%. Completely different texts score 0%.
Is this text diff tool free?
Yes, completely free with no account or signup required. All diff computation happens entirely in your browser using a native Myers diff implementation. No text is ever sent to any server.
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