Paste text in both panels and click Compare
How to Use This Tool
Step 1
Paste your texts
Paste the original text on the left and the modified version on the right. Or click Sample to load example data.
Step 2
Click Compare
Additions show in green, deletions in red. Within changed lines, modified words are highlighted for precise identification.
Step 3
Toggle options
Switch between side-by-side and inline views. Ignore whitespace or case differences to focus on meaningful changes.
Step 4
Review stats
The stats bar summarizes added, removed, and unchanged lines. Use Swap to reverse the comparison direction.
Frequently Asked Questions
What is a diff?
A diff (short for difference) is a structured comparison showing what changed between two versions of text. The concept originated with the Unix
diff command created by Douglas McIlroy in the early 1970s. Today, diffs are the foundation of version control — every Git commit, pull request, and code review is powered by diff algorithms that identify the minimum set of changes needed to transform one text into another.What is the difference between side-by-side and inline diff?
Side-by-side (split) diff shows the original and modified texts in two columns with matching lines aligned horizontally. This is best for reviewing structural changes and seeing context on both sides. Inline (unified) diff interleaves both texts in a single column, with deletions prefixed by
- and additions by +. Inline is more compact and is the default format for Git, patch files, and code review tools like GitHub.What algorithm does this tool use?
This tool uses a longest common subsequence (LCS) diff algorithm. It first compares texts line by line to identify added, removed, and matching lines. Then, for lines that exist in both versions but differ, it performs word-level diffing to highlight exactly which words changed within each line. This two-pass approach gives you both the high-level structural view and precise change identification.
Is my data sent to a server?
No. All text comparison happens entirely in your browser using JavaScript. Your data never leaves your device.