Text Diff Checker
Paste or type two versions of a text below, then click Compare to see what changed. Added lines are highlighted, removed lines are marked, and a summary shows the total changes.
Click "Compare" to see differences…About this tool
The Text Diff Checker compares two blocks of text line by line and highlights every difference. Writers use it to track changes between drafts before handing copy to an editor. Developers compare configuration files, log outputs, or code snippets to spot what changed between versions. Editors verify that requested revisions were applied correctly without introducing unintended modifications. The tool uses a Longest Common Subsequence (LCS) algorithm to accurately detect added, removed, and unchanged lines, even when large blocks are rearranged. Three comparison options — Ignore Case, Ignore Whitespace, and Ignore Empty Lines — let you focus on meaningful differences. Everything runs in your browser; no text is ever uploaded or stored.
How to use
- Paste your Original text in the left textarea and your Modified text in the right textarea.
- Toggle any comparison options: Ignore Case, Ignore Whitespace, or Ignore Empty Lines.
- Click Compare to run the diff. Added lines are highlighted in blue, removed lines in red, and unchanged lines in neutral grey.
- Use the Copy button to copy the diff output as text, or click Load Sample to try with example text.
Frequently Asked Questions
How does the diff algorithm work?
The tool uses the Longest Common Subsequence (LCS) algorithm to compare texts line by line. This is the same algorithm used by version control systems like Git. It accurately determines which lines were added, removed, or left unchanged, even when content is rearranged.
What is the difference between the comparison options?
Ignore Case treats "Hello" and "hello" as the same line. Ignore Whitespacetreats "hello world" and "hello world" as identical by collapsing extra spaces. Ignore Empty Lines removes blank lines from both texts before comparing, useful when whitespace formatting differs between documents.
Is there a limit on text size?
The tool can handle texts up to 5,000 lines each. Beyond that, the comparison may become slow due to the O(n×m) complexity of the LCS algorithm. For most real-world use cases — comparing document drafts, config files, or code snippets — performance is instantaneous.
Does this tool send my text anywhere?
No. Everything runs entirely in your browser. No text is uploaded, stored, or shared with any server. Your data stays completely private.
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