Text & Code Diff Checker - Compare Files and Find Differences

Each comparison mode offers different granularity and usefulness depending on your content:

• Character by Character: The most detailed comparison, highlighting each individual character that differs. Perfect for finding subtle text changes like typos or punctuation.
• Word by Word: Compares text as discrete words, making it easier to spot added, removed, or changed words in sentences. This is generally the most useful mode for text documents.
• Line by Line: Compares content line by line, showing which lines were added, removed, or changed. Best for code where each line is a logical unit.
• Sentence by Sentence: Groups changes by complete sentences, ideal for comparing paragraphs of text in articles or documentation.

The specialized CSS and JSON modes use syntax-aware algorithms to provide meaningful comparisons for those specific formats, understanding their structure rather than treating them as plain text.

Our diff checker provides highly accurate results for code files using industry-standard algorithms. It employs the same core comparison engines used in popular version control systems like Git.

For code files specifically, we recommend:

• Using the Line by Line comparison mode for most programming languages
• Enabling syntax highlighting to make the differences more readable
• Using the language-specific modes for CSS and JSON files
• Enabling the "Ignore whitespace" option to focus on actual code changes rather than formatting

For the most accurate results with minified code, consider formatting the code first using our JavaScript Beautifier or similar tools before comparing.

Since this tool runs entirely in your browser:

• The practical limit is around 2MB per file for most browsers
• For files larger than 500KB, performance may begin to degrade
• Very complex diffs with thousands of changes may take longer to process and display

For comparing extremely large files (10MB+), we recommend using a desktop application like Beyond Compare or the command-line tools like GNU diff that are designed to handle such files more efficiently.

Your files are never uploaded to any server - all processing happens locally in your browser, ensuring privacy and security but limiting the maximum file size based on your device's capabilities.

No, this diff checker is designed specifically for text-based files. It cannot effectively compare binary files or images. Here's what you should know:

• The tool works with any text-based format: plain text, source code, markup languages, configuration files, etc.
• Binary files like images (JPG, PNG), PDFs, Word documents, or executable files cannot be meaningfully compared using text-based diff tools
• If you need to compare binary files, consider specialized tools designed for those specific formats

For some binary formats that have text representations (like Word documents), you may be able to extract the text content first and then use this tool to compare the text portions.

Yes, your data is completely safe when using our diff checker:

• Client-side processing: All comparison operations are performed entirely in your browser. Your text/code is never sent to our servers.
• No data storage: We don't store any of your content. When you close the browser tab or refresh the page, all data is cleared.
• No authentication required: You can use the tool anonymously without creating an account.
• Secure connection: The website uses HTTPS to ensure secure communication between your browser and our servers.

This makes our diff checker suitable even for sensitive or confidential content. However, if you're working with highly classified information, always follow your organization's security protocols.

While this online tool doesn't provide direct API access, you can implement similar functionality in your own applications using the same open-source libraries:

• diff: A JavaScript library that provides the core diff algorithms (character, word, line, etc.)
• diff2html: For rendering the differences in a visually appealing way
• CodeMirror: For the editor functionality with syntax highlighting

These libraries are available on npm and can be integrated into any JavaScript application. For server-side implementations, similar libraries exist for most programming languages (e.g., Python's difflib, Java's DiffUtils).

Check the documentation of these libraries for detailed integration instructions, or consider using a Git-based approach for version control systems.

The two main visualization modes offer different ways to understand the differences:

• Side by Side (line-by-line): Shows the original and modified text in parallel columns, making it easy to align and compare corresponding sections. Changes are highlighted in both columns for clear identification. This is generally better for visual comparison and understanding context.
• Unified View: Combines both files into a single view, using + and - symbols to indicate additions and deletions. This format is more compact and similar to what you'd see in git diff output or patch files. It's better for situations where screen space is limited.

Side by side is usually preferred for detailed review and analysis, while unified view is more compact and better for sharing via email or documentation.

The similarity percentage is calculated based on the Levenshtein distance algorithm, adapted for the selected comparison mode:

• The tool counts the total number of tokens (characters, words, or lines, depending on the selected mode)
• It then counts how many operations (insertions, deletions, or substitutions) would be needed to transform the original text into the modified text
• The similarity is calculated as: (1 - (number of operations / total tokens)) × 100%

For example, if comparing two texts with 100 words total, and 10 operations are needed to make them identical, the similarity would be 90%.

The similarity calculation may vary slightly between different comparison modes, as each mode tokenizes the content differently.