Free Online Text Diff Checker
Compare two texts side by side with highlighted differences. Supports line-by-line and word-by-word diff modes with split and unified view. Download results as a standard .diff patch file. All comparison happens in your browser.
🔒 All text comparison occurs 100% locally in your web browser. No text is ever uploaded.
How to Use Text Diff Checker
- Paste Original Text: Paste or type the original version of your text into the left panel labeled 'Original'.
- Paste Modified Text: Paste or type the new or modified version into the right panel labeled 'Modified'.
- Choose Diff Mode: Select 'Line by Line' for a paragraph or document comparison, or 'Word by Word' for detecting granular changes within sentences.
- Review & Export: Review differences highlighted in green (added) and red (removed). Switch between Split and Unified views, or download the result as a standard .diff patch file.
Operational Limits & Specifications
| Processing Tier | Client-Side (In-Browser Execution) |
|---|---|
| Max File Size | 10 MB per file |
| Max Batch Quantity | Up to 2 files |
| Max Total Batch Size | 10 MB total |
| Supported Formats | .txt, .diff, .patch, .md, .json, .cs, .js |
Common Use Cases
Code Review & Patch Inspection
Compare two source code files to inspect algorithmic changes, bug fixes, or refactoring before committing to Git.
Legal Contract & Agreement Auditing
Identify subtle clause alterations, additions, or deleted terms between contract versions.
Content Editorial & Revision Tracking
Track modifications made between original draft manuscripts and final edited copy.
Configuration Drift Analysis
Compare staging and production environment configuration files (YAML, JSON, INI) to identify configuration drift.
Technical Mechanics & Architecture
Comparison with Alternatives
Tips & Troubleshooting
- Switch to 'Word by Word' mode when comparing sentences or paragraphs to pinpoint exact phrasing changes within lines.
- Use 'Split View' on desktop monitors for side-by-side comparison; use 'Unified View' on mobile screens or for Git-style diff inspection.
- Download your comparison as a standard .diff patch file to share modifications with colleagues or apply with git apply.
- For large multi-thousand line files, enable line-by-line mode for optimal rendering performance.
Frequently Asked Questions
What algorithm does the diff tool use?
The tool uses the Longest Common Subsequence (LCS) / Myers diff algorithm, the same underlying algorithm used by Git, diff, and patch utilities, finding the minimum set of changes required to transform the original text into the modified text.
What is the difference between Split and Unified views?
Split view displays original and modified text in two side-by-side synchronized panels. Unified view combines both into a single stream with '+' prefixes for added lines and '-' prefixes for removed lines, similar to standard git diff output.
Can I compare code files and scripts?
Yes. The diff checker supports any plain text format including C#, JavaScript, Python, HTML, CSS, JSON, YAML, Markdown, and SQL.
Is there a limit on text length?
The tool handles documents with thousands of lines smoothly in modern browsers. Performance depends on available device memory since all computation runs locally.
Are my confidential documents uploaded to any server?
No. All text comparison occurs 100% locally in your browser memory. Your documents and code are never transmitted over the internet.
Can I export the diff result?
Yes. You can download the comparison result as a standard .diff patch file compatible with standard patch and git tooling.