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Text Diff Checker

Compare two texts and see every addition, deletion, and change highlighted.

100% freeRuns in browserNo data sent to servers
Original
Modified

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How It Works

1

Paste both texts

Enter the original text on the left and the modified version on the right. Or click Sample to load example code.

2

Compare

Click Compare to run the diff. Toggle word-level diff or ignore whitespace for finer control.

3

Review changes

Added lines show in green, removed in red. Use Swap to flip the comparison direction.

FAQ

How does the diff algorithm work?
It uses a line-by-line comparison that identifies additions (green), deletions (red), and unchanged lines. Lines are compared after normalizing whitespace for accurate results.
Can I compare code files?
Yes. The diff checker works well with any text including source code, configuration files, documentation, and prose. It preserves formatting and whitespace.
Is there a size limit?
There is no hard limit, but very large texts (over 100,000 lines) may be slow since all processing happens in your browser.
Can I diff files larger than a few thousand lines?
Yes, but performance degrades with very large inputs because all processing runs in the browser. For files over 10,000 lines, use the command-line "diff" tool or "git diff" which are optimized for large texts. This tool is ideal for quick comparisons of config snippets, API responses, and document versions.
Does the diff show syntax highlighting for code?
The diff uses color to indicate added (green background) and removed (red background) lines. It does not apply language-specific syntax highlighting within each line. For code review with full syntax highlighting, use a diff tool integrated into your IDE or GitHub's pull request diff view.
How is this different from git diff?
Git diff tracks changes between versions in a repository using a unified diff format with @@ hunk headers. This tool compares two arbitrary text inputs directly, without any repository context. It is useful when you do not have git history -- for example, comparing two API responses, two config file versions pasted from different sources, or two drafts of a document.

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Coda One's Text Diff Checker is a free online developer tool that runs entirely in your browser. No data is sent to any server -- everything is processed locally for maximum privacy and speed. Part of the Coda One developer tools suite.

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