Diff Checker
Compare two text blocks side by side and see every difference highlighted instantly. All processing happens in your browser.
What is a Diff Checker?
A diff checker (also called a text compare tool) compares two blocks of text and visually highlights the differences. It identifies lines that have been added, removed, or modified between the two versions. Diff checking is fundamental to software development, document editing, and any workflow that involves tracking changes over time.
How Does Text Comparison Work?
This tool uses the longest common subsequence (LCS) algorithm to find the optimal alignment between two texts. It compares the input line by line, identifies matching and differing lines, and then performs word-level comparison within modified lines to pinpoint the exact changes. The result is a clear, color-coded view of every difference.
Split View vs Unified View
Split view displays the original and modified text side by side, with corresponding lines aligned and line numbers shown. This is ideal for wide screens and makes it easy to see how specific lines changed. Unified view combines both texts into a single column, with removed lines prefixed by - and added lines prefixed by +. Unified view is the format used by git diff and works well on narrower screens.
Comparison Options
| Option | What It Does | When to Use |
|---|---|---|
| Ignore Whitespace | Treats lines as equal if they differ only in spaces or tabs | Comparing reformatted code or varying indentation styles |
| Ignore Case | Treats uppercase and lowercase letters as identical | Comparing case-insensitive data like SQL or HTML tags |
| Swap Sides | Exchanges the original and modified inputs | Quickly reversing the comparison direction |
| Inline Diff | Highlights word-level changes within modified lines | Pinpointing exact edits within long lines |
Frequently Asked Questions
What is a diff checker?
A diff checker compares two blocks of text and highlights the differences between them. Added lines are shown in green, removed lines in red, and modified lines in yellow with word-level highlighting. It is essential for code review, document comparison, and tracking changes between file versions.
What is the difference between split view and unified view?
Split view shows the original and modified text side by side with line numbers, making it easy to compare corresponding lines. Unified view combines both texts into a single column with removed lines prefixed by '-' and added lines prefixed by '+', similar to git diff output. Split view is ideal for wide screens, while unified view works well on narrower screens.
What does 'ignore whitespace' do?
The ignore whitespace option treats lines as identical even if they differ only in spaces, tabs, or trailing whitespace. This is useful when comparing code that may have been reformatted or when indentation style differs between versions, letting you focus on meaningful content changes.
Is my data safe when using this diff tool?
Yes. All comparison happens entirely in your browser using JavaScript. No text is sent to any server. Your data never leaves your device, making it safe to compare sensitive code, configuration files, and private documents.
Can I compare code files with this tool?
Absolutely. This diff checker works with any plain text including source code in any programming language, configuration files, JSON, XML, Markdown, and more. It provides line numbers and word-level highlighting within modified lines to pinpoint exact changes.
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