How to Use This Tool
Enter Original Text
Compare text online for free - paste the original version into the Original panel, click Upload to select a .txt file, or drag and drop a file onto the area.
Enter Modified Text
Paste the modified version into the Modified panel, upload a file, or drag and drop. Each panel has its own Upload button and drop zone.
Review Differences
The diff appears instantly below. Red lines (-) were removed from the original, green lines (+) were added in the modified version, and gray lines are unchanged.
Copy or Download
Use Copy Difference to copy the diff to your clipboard, or Download Difference to save as a .txt file. Click Clear All to reset both panels.
Text Comparison FAQ - Frequently Asked Questions
Is my text uploaded to a server?
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No. This tool runs 100% in your browser. Your text is never uploaded anywhere. All comparison happens entirely on your device.
How does the comparison work?
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The tool compares text line by line. Removed lines appear in red, added lines appear in green, and unchanged lines are shown in gray. It finds the optimal alignment between both texts for accurate results.
What happens with large texts?
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For inputs over 500 lines, the tool automatically switches to a faster comparison mode to avoid browser slowdowns. This may show slightly more differences for texts with large inserted or deleted sections.
Can I compare files directly?
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Yes. Each panel (Original and Modified) has its own Upload button and drag-and-drop zone. You can upload .txt files directly without opening them in a text editor first.
What format is the diff output?
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The diff uses unified format with + and - markers. Lines prefixed with - were removed from the original, lines prefixed with + were added in the modified version.
Can I download the diff?
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Yes. Click Download Difference to save the diff as a text-diff.txt file. You can also click Copy Difference to copy it to your clipboard.
Is the comparison case-sensitive?
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Yes. The comparison is both case-sensitive and whitespace-sensitive. A line with different capitalization or trailing spaces is treated as a different line.
Is my data saved if I refresh?
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No. This tool does not save your text. Refreshing the page clears both panels. Copy or download your diff before leaving the page.
What Is a Text Difference Comparison Tool?
A text difference comparison tool (also called a text diff tool) compares two blocks of text line by line and highlights what changed between them. Lines that were removed appear in red, lines that were added appear in green, and unchanged lines are shown in gray. This is the same type of comparison used by version control systems and code review platforms.
This free online text diff tool runs 100% in your browser - your text is never sent to any server. It supports file upload, drag and drop, and handles texts up to thousands of lines. Copy or download the diff output for sharing or record keeping.
Text Diff Features
Accurate Line-by-Line Comparison
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Finds the optimal alignment between both texts to produce minimal, accurate diffs. The same approach used by professional version control and code review systems.
Large File Support
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For inputs over 500 lines, the tool automatically switches to a faster positional comparison to avoid browser slowdowns. This trades some diff accuracy for performance on very large texts.
Unified Diff Output
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The diff is shown with + and - markers. You can copy or download it in standard unified diff format, compatible with code review and patch workflows.
Per-Panel File Upload
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Each panel (Original and Modified) has its own Upload button and drag-and-drop zone. Compare two files directly without manual copy-paste.
Real-Time Stats
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A statistics line above the diff shows the count of removed lines (red), added lines (green), and unchanged lines - updated instantly as you type.
Who Needs to Compare Text Online?
Web Developers
Compare code versions, review changes before committing, or debug differences between configuration files across environments.
Writers
Compare document drafts to see exactly what changed between revisions. Identify added, removed, and modified paragraphs at a glance.
Editors
Verify editorial changes by comparing original and edited manuscripts. Ensure all requested revisions were applied correctly.
QA Engineers
Compare expected vs actual test outputs, verify responses between staging and production, and detect unexpected changes in data.
System Administrators
Compare server configurations, deployment scripts, and log files across different environments to detect discrepancies.
Students
Compare assignment drafts, study notes, or code submissions to identify what changed between versions.
Legal Professionals
Compare contract versions, policy updates, and regulatory text to identify exactly which clauses were added, removed, or modified.
Project Managers
Compare requirement documents, specifications, and project plans between versions to track scope changes.
Technical Writers
Compare documentation versions to verify all updates were applied and no unintended changes were introduced.
Database Administrators
Compare schema definitions, migration scripts, and stored procedures between database versions.
DevOps Engineers
Compare infrastructure-as-code files, CI/CD configurations, and deployment manifests between releases.
Content Managers
Compare CMS content versions, website copy, and marketing materials to track editorial changes over time.
Translators
Compare source text versions to identify what changed, so only the modified sections need retranslation.
Teachers
Compare student submissions against each other or against answer keys to check for similarities and differences.
Data Analysts
Compare CSV exports, query results, and data snapshots to identify changes in datasets over time.
Security Analysts
Compare configuration files and access control lists before and after changes to audit security modifications.
Compliance Officers
Compare policy documents and regulatory filings between versions to ensure all required updates were made.
Researchers
Compare versions of academic papers, grant proposals, and literature review notes to track revisions.
HR Professionals
Compare job descriptions, employee handbook versions, and policy documents to track organizational changes.
Freelancers
Compare client feedback versions, project briefs, and deliverable specifications to track requirement changes.
API Developers
Compare API response payloads between versions to verify backwards compatibility and detect breaking changes.
Email Marketers
Compare email template versions, subject line variations, and campaign copy between A/B test iterations.
Accountants
Compare financial reports, tax filing drafts, and ledger entries between periods to identify changes.
Everyone
Compare any two texts online for free - paste, upload, or drag and drop files and see differences instantly.
Text Diff Legend
| Marker | Color | Meaning |
|---|---|---|
| - | Red | Line was removed from the original text |
| + | Green | Line was added in the modified text |
| (none) | Gray | Line is identical in both versions |
Tips for Comparing Text Differences
Order matters
Put the older version in Original and the newer version in Modified. This way, red lines show what was removed and green lines show what was added.
Upload files directly
Each panel has its own Upload button and drag-and-drop zone. Compare two files without opening them in a text editor first.
Download the diff
The Download button saves the diff with + and - markers. This format is compatible with code review and patch workflows.
Large files use fast mode
Files over 500 lines automatically use a faster positional comparison. This may show more differences for texts with large inserted or deleted sections.
Check whitespace differences
The diff is whitespace-sensitive. A line with a trailing space is different from one without. Clean up whitespace first if those differences are not relevant.
Combine with other tools
Use our Sort Lines tool to sort both inputs before comparing to find content differences regardless of order.
Privacy & Security
This tool runs 100% in your browser. Your text is never uploaded to any server. The diff comparison happens entirely on your device.
Use the Clear All button to remove both texts at any time. No cookies are used, no analytics track your text content, and no third-party services have access to what you type.