Text Compare

Getting Started

Follow these simple steps to compare two texts side by side and find differences instantly:

• Step 1: Switch to the Utility tab at the top of the page.
• Step 2: Paste or type the original text into the Left Text panel.
• Step 3: Paste or type the modified text into the Right Text panel.
• Step 4: Differences are highlighted automatically in real time — red marks removed text, green marks added text.

Comparison Modes

Choose the comparison granularity that best fits your needs. Our text diff tool online supports three modes:

• Word Mode — Compares text word by word. Best for prose, articles, and general writing. Each changed word is highlighted individually so you can see exactly which words were added, removed, or replaced.
• Line Mode — Compares text line by line. Ideal for code, configuration files, and structured text. Displays a merge gutter between panels with arrow buttons to copy changes from one side to the other.
• Character Mode — Compares text character by character. Perfect for catching subtle differences like typos, spacing changes, or punctuation edits that word-level comparison might group together.

Example: Comparing Two Paragraphs

Try pasting these two versions to see the diff tool in action:

Left (Original):

• The quick brown fox jumps over the lazy dog. It was a sunny day and the fox was happy.

Right (Modified):

• The quick red fox leaps over the lazy cat. It was a cloudy day and the fox was tired.

In Word mode, you will see "brown" highlighted as removed and "red" as added, "jumps" removed and "leaps" added, "dog" removed and "cat" added, and so on.

Comparison Options

Fine-tune your comparison with these options available in the toolbar:

• Ignore Whitespace — Treats multiple spaces, tabs, and trailing whitespace as equal. Useful when comparing text from different sources that may have inconsistent formatting.
• Ignore Case — Makes the comparison case-insensitive, so "Hello" and "hello" are treated as identical. Great for comparing text where capitalization differences are not important.

Merging Differences

In Line mode, arrow buttons appear in the center gutter next to each difference. Use these merge controls to selectively copy changes between panels:

• Right arrow — Copies the change from the left panel to the right panel.
• Left arrow — Copies the change from the right panel to the left panel.

Changes update instantly, and the diff recalculates automatically after each merge operation.

Navigation & Toolbar

Use the toolbar buttons to navigate and manage your text comparison:

• Previous / Next — Jump between differences using the navigation arrows and the diff counter (e.g., "3/7") to track your position.
• Swap — Swap the left and right panel contents with a single click.
• Reset — Clear both panels and start a fresh comparison.
• Copy — Copy the diff summary to your clipboard.
• Export — Download the diff results as a JSON file for archiving or further processing.
• Load — Upload a text file directly into either panel. Supports common file types including .txt, .md, .json, .xml, .html, .css, .js, and more.
• Clear — Clear an individual panel without affecting the other side.

Example: Word Mode Comparison

Word mode is the default and most commonly used comparison. Try pasting these texts:

Left:

• The application uses a MySQL database for data storage.

Right:

• The application uses a PostgreSQL database for data retrieval.

Result: "MySQL" is highlighted in red (removed) and "PostgreSQL" in green (added). "storage" is highlighted in red and "retrieval" in green. The remaining words appear without highlighting because they are identical in both versions.

Example: Line Mode Comparison with Merge

Line mode is ideal for comparing structured text like code or configuration. Try these inputs:

Left:

• host: localhost
port: 3000
debug: true
timeout: 30

Right:

• host: localhost
port: 8080
debug: false
timeout: 30

Result: Lines 1 and 4 show no highlighting (identical). Line 2 ("port: 3000" vs "port: 8080") and Line 3 ("debug: true" vs "debug: false") are highlighted as differences. The merge gutter shows colored bars and arrow buttons next to lines 2 and 3, allowing you to copy either version to the other panel.

Example: Character Mode Comparison

Character mode catches subtle single-character differences. Try these inputs:

Left:

• recieve the package

Right:

• receive the package

Result: In character mode, the "ie" in "recieve" is highlighted red and "ei" in "receive" is highlighted green, pinpointing the exact character swap. Word mode would highlight the entire word as changed, while character mode shows exactly which letters differ — making it perfect for catching typos and spelling corrections.

Note: For very large texts (over 8,000 characters combined), character mode automatically switches to word mode to maintain performance. A notification appears in the status area when this happens.

Synchronized Scrolling

Both text panels scroll together so corresponding sections stay aligned as you scroll through long documents. This synchronized scrolling also applies to the diff highlight overlays and the merge gutter in line mode, ensuring visual consistency across all elements.

How to Export Diff Results

Click the Export button to download the comparison results as a JSON file. The exported file contains complete metadata about the comparison:

• mode — The comparison mode used (word, line, or char).
• ignoreWhitespace — Whether whitespace was ignored.
• ignoreCase — Whether case was ignored.
• timestamp — The date and time of the comparison in ISO format.
• left — The full text from the left panel.
• right — The full text from the right panel.
• diff — An array of diff objects, each with a type (equal, removed, or added) and value (the text content).
• summary — A text summary of the differences (e.g., "5 differences: 2 removed, 3 added, 12 unchanged words").

The exported JSON file is named text-diff-[timestamp].json and can be used for documentation, automated processing, or archival purposes.

File Upload Support

Both panels support file upload via the Load button. You can load text files directly into either the left or right panel without copy-pasting. Supported file formats include:

• Text files — .txt, .md, .csv, .log
• Code files — .js, .ts, .py, .java, .go, .rs, .c, .cpp, .h
• Markup files — .json, .xml, .html, .css

You can also use keyboard navigation: press Enter or Space on the Load button to open the file dialog. Files are read using the browser's FileReader API and loaded directly into the textarea.

Use Cases for Text Comparison

Our online text compare tool is useful for a wide range of tasks:

• Proofreading — Compare drafts of an article, essay, or email to see exactly what changed between revisions.
• Code Review — Compare two versions of source code to identify modifications, additions, and deletions before committing.
• Document Versioning — Track changes between contract revisions, policy updates, or specification documents.
• Translation Verification — Compare original and translated text side by side to ensure nothing was missed.
• Content Auditing — Detect unauthorized changes in website copy, legal text, or published content.

What is Text Diff?

A text diff (short for "difference") is the result of comparing two pieces of text to identify what has changed between them. Diff tools highlight additions, deletions, and modifications so you can see exactly what is different without reading both texts line by line.

The concept of text diffing originated in Unix with the diff command, created by Douglas McIlroy in 1974. Today, diff algorithms are the foundation of version control systems like Git, code review platforms like GitHub, and document collaboration tools like Google Docs.

Our online text compare tool uses the Myers diff algorithm — the same algorithm used by Git — to compute the minimum set of changes needed to transform one text into another. This ensures accurate, efficient results even for large documents.

Understanding Diff Output

When you compare two texts, our diff tool uses color coding to show exactly what changed:

• Red highlighting — Text that was removed or deleted from the original (left panel). This content exists in the left text but not in the right text.
• Green highlighting — Text that was added or inserted in the modified version (right panel). This content exists in the right text but not in the left text.
• No highlighting — Text that is identical in both versions. Unchanged content provides context around the differences.

The diff counter in the toolbar (e.g., "3/7") shows your current position and the total number of differences found, making it easy to navigate through changes systematically.

Choosing the Right Comparison Mode

Different comparison granularities serve different purposes. Here is when to use each mode:

• Word Mode (default) — Best for comparing prose, articles, emails, and general text. Shows which individual words changed without splitting at the character level. Use this when you want to see meaningful content changes while ignoring minor formatting differences.
• Line Mode — Best for comparing code, configuration files, CSV data, and structured text where each line is a distinct unit. This is the only mode that enables the merge gutter with arrow buttons for selectively copying changes. Use this when you need the familiar side-by-side diff view used in code review tools.
• Character Mode — Best for finding subtle differences like typos, extra spaces, punctuation changes, or single-character edits. Use this when word-level comparison groups too many changes together and you need to see the exact characters that differ.

Tips for Effective Text Comparison

Get the most accurate and useful results from your text comparisons with these tips:

• Normalize formatting first — If you are comparing text from different sources (e.g., Word vs plain text), the formatting may differ even if the content is the same. Use "Ignore whitespace" to filter out formatting noise.
• Use Ignore Case for content comparison — When you only care about content changes and not capitalization differences, enable "Ignore Case" to reduce false positives.
• Start with Word mode — Word mode gives you the best overview of meaningful changes. Switch to Line or Character mode only when you need more granularity.
• Use the navigation arrows — For long documents with many differences, use the Previous/Next buttons to jump between changes instead of scrolling manually.
• Export for documentation — Use the Export button to save the diff results as JSON. This creates a permanent record of changes that you can share with colleagues or attach to documentation.
• Load files directly — Instead of copy-pasting from files, use the Load button to upload text files directly into either panel. This preserves the original formatting and avoids clipboard issues.

Performance

The diff algorithm runs in a Web Worker off the main thread, so the user interface stays responsive even with large text inputs. Adaptive debouncing ensures smooth typing — shorter delays for small text and longer delays for large documents. Diff results are rendered in batches to minimize DOM operations.

Privacy

Your text is processed entirely in your browser using JavaScript. Nothing is ever sent to any server — your data stays on your device, always. There is no tracking, no account required, and no data collection of any kind. Learn more in our Privacy Policy.

Frequently Asked Questions

How do I compare two texts online for free?

Paste or type your original text in the left panel and the modified text in the right panel. Differences are highlighted automatically in real time — no button click needed. You can switch between line, word, and character comparison modes.

Can I merge differences between two texts?

Yes. In line mode, arrow buttons appear in the center gutter next to each difference. Click the right arrow to copy a change from left to right, or the left arrow to copy from right to left. Changes update instantly.

Does this text compare tool work with large files?

Yes. The diff algorithm runs in a Web Worker off the main thread, so the UI stays responsive even with large text inputs. An adaptive debounce ensures smooth typing for texts of any size.

Can I ignore whitespace or case when comparing text?

Yes. Use the "Ignore whitespace" checkbox to treat multiple spaces, tabs, and trailing whitespace as equal. Use "Ignore case" to make the comparison case-insensitive.

Is my text safe when using this diff tool?

Your text never leaves your device. All comparison and diff processing happens locally in your browser — no data is sent to any server. Learn more in our Privacy Policy.