How does the code diff work?

It uses a Longest Common Subsequence (LCS) algorithm to find matching lines and highlights additions, removals, and unchanged lines with line numbers.

What languages are supported?

The diff is language-agnostic. It compares plain text line by line so it works with any programming language or text format.

What do the colours mean?

Green background indicates lines added in the modified version. Red background indicates lines removed from the original.

Is my code sent to a server?

No. All comparison runs entirely in your browser. Your code never leaves your device.

Code Diff Checker

Compare two code snippets and see differences highlighted line by line.

Original

Modified

How to Use Code Diff Checker

Step 1

Paste the original code into the left textarea.

Step 2

Paste the modified code into the right textarea.

Step 3

Click Compare to run the diff.

Step 4

Review the highlighted output with line numbers below.

Features

Line-by-line diff with LCS algorithm.

Line numbers for easy reference.

Added lines highlighted in green, removed in red.

Monospace font throughout for code readability.

Completely client-side — no data leaves your browser.

FAQ

: It uses a Longest Common Subsequence (LCS) algorithm to find matching lines and highlights additions, removals, and unchanged lines with line numbers.
: The diff is language-agnostic. It compares plain text line by line so it works with any programming language or text format.
: Green background indicates lines added in the modified version. Red background indicates lines removed from the original.
: No. All comparison runs entirely in your browser. Your code never leaves your device.