What algorithm is used for diffing?

Word and line diffs use the Longest Common Subsequence (LCS) algorithm; character diff applies LCS at the character level.

How is similarity percentage calculated?

It is calculated as 2 × matched tokens / (total tokens in original + total tokens in new text) × 100.

What is the difference between word and character diff?

Word diff compares individual words; character diff compares every single character, showing fine-grained changes within words.

Is there a text size limit?

Very large texts (tens of thousands of words) may slow down the browser due to the LCS algorithm's complexity. For best performance keep texts under 5 000 words each.

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Text Diff Highlighter

Compare two texts with word-level, character-level, or line-level diff highlighting.

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About this tool

Paste two pieces of text and instantly see what changed. Switch between word-level, character-level, and line-level diff modes. Added content is highlighted in green, removed content in red with strikethrough, and a similarity score is shown.

How to use

1 Step 1: Paste or type your original text in the left panel.
2 Step 2: Paste or type the new/modified text in the right panel.
3 Step 3: Choose a diff mode: Word, Character, or Line.
4 Step 4: View the highlighted diff inline or toggle to side-by-side view, and check the stats summary.

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How to use

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