Diff Checker
Compare two texts and highlight the differences. Runs entirely in your browser.
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Modified
How the Text Diff Checker Works — Side-by-Side Comparison Like VS Code
This diff tool compares two texts line by line using an LCS (Longest Common Subsequence) algorithm — the same approach used by Git, VS Code, and other professional diff tools. It identifies additions (green), deletions (red), and modifications (changed lines with word-level highlighting showing exactly what changed within each line).
Features of This Diff Checker
- Side-by-side view — VS Code-style split panels showing original text on the left and modified text on the right
- Line-level highlighting — Added lines highlighted in green, deleted lines in red
- Word-level highlighting — For modified lines, specific changed words are highlighted within the line for precise comparison
- Line numbers — Both panels show line numbers for easy reference
- Synchronized scrolling — Both panels scroll together for easy comparison of large texts
- Diff statistics — Summary of total additions, deletions, and modifications
Common Use Cases for Text Comparison
- Code review — Compare two versions of a file to see what changed before committing
- Configuration comparison — Diff production vs staging config files, .env files, or YAML/JSON configs
- API response debugging — Compare expected vs actual JSON responses
- Document revision tracking — See what changed between two drafts of a document, blog post, or email
- Database record comparison — Paste two rows or records to spot field-level differences
- Merge conflict resolution — Compare conflicting versions when resolving Git merge conflicts
Understanding Diff Output Colors
- Green background — Line or word was added in the modified text
- Red background — Line or word was deleted from the original text
- Highlighted words within lines — Specific words that changed within a modified line, making it easy to spot small changes
Frequently Asked Questions
This tool uses the Myers diff algorithm, the same algorithm used by Git and most code editors. It finds the minimum number of edits (insertions and deletions) needed to transform one text into the other, then highlights the differences at both line and word level.
The diff checker compares any plain text including source code, configuration files, JSON, XML, SQL, and more. It highlights additions in green and deletions in red with word-level precision, similar to VS Code's built-in diff view. Paste your code in both panels and click Compare.
Yes. Beyond line-level diff, the tool performs word-level highlighting within changed lines. This makes it easy to spot exactly which words or characters were modified, added, or removed — especially useful for reviewing small changes in long lines of code.
No. All text comparison runs entirely in your browser using JavaScript. Your data never leaves your device — no text is transmitted to any server. This makes it safe for comparing proprietary code, contracts, and confidential documents.
There is no hard limit, but performance depends on your browser and device. The tool handles files up to several thousand lines efficiently. For very large files (10,000+ lines), the diff computation may take a moment. Splitting large files into smaller sections can improve responsiveness.