Text Diff Checker
Compare two texts and highlight differences instantly. Free online diff checker with line-by-line comparison.
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What is Text Diff Checker?
A diff checker compares two texts line by line and highlights the differences between them. Added lines appear in green, removed lines in red, and changed lines are clearly marked. This is useful for comparing document revisions, verifying code changes, checking configuration file differences, and reviewing edits before publishing.
How to Use
- Paste the original text in the left (Before) panel
- Paste the modified text in the right (After) panel
- Click Compare to see the differences highlighted
- Green lines are additions, red lines are deletions, and changes are clearly visible
Examples
Compare two versions
Find added lines
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Frequently Asked Questions
How is the diff computed?
The tool uses the Longest Common Subsequence (LCS) algorithm to find the optimal alignment between the two texts. This produces an accurate diff that correctly identifies added, removed, and changed lines.
Does formatting affect the comparison?
Yes. The comparison is line-based and exact. A trailing space or different indentation will cause a line to be shown as changed. Trim whitespace first if you want to ignore formatting differences.
Is there a size limit?
The tool handles texts up to several thousand lines. Very large files (10,000+ lines) may cause browser slowdowns since the diff algorithm has quadratic time complexity.