What algorithm does this use?

It uses a Longest Common Subsequence (LCS) algorithm at the line level — the same approach used by git diff.

Can I compare code files?

Yes! Paste any text including code. The comparison is line-by-line so it works well for code, prose, config files, etc.

What do the colors mean?

Green lines with + were added (in Modified but not Original). Red lines with − were removed (in Original but not Modified). Unchanged lines are shown without color.

Is my text sent to a server?

No. All comparison happens in your browser. Your text never leaves your device.

Yes. Click "Copy Diff" to copy the unified diff format with + and − prefixes.

ToolsArena

Text Diff Checker

Compare two texts side-by-side and highlight the differences line by line.

+3 added−2 removed2 unchanged

Original

Modified

Diff Result

	The quick brown fox
−	jumps over the lazy dog
−	Hello World
+	leaps over the lazy cat
+	Hello World!
	Line four here
+	New line added

How to Use Text Diff Checker

1
Paste the original text in the left panel.
2
Paste the modified text in the right panel.
3
View differences highlighted in the diff result below.
4
Switch between Split and Unified views.
5
Click "Copy Diff" to export the diff.

About Text Diff Checker

Paste two versions of a text and instantly see what was added, removed, or unchanged. Uses a line-level LCS diff algorithm — similar to git diff. Split and unified views. Copy the diff output with one click.