Text Diff Checker

Compare two texts and highlight differences.

LocalYour data is processed locally in your browser and is not uploaded to Alphzen.

Line-based comparison. This is not a git patch and not a merge tool.

Original

function greet(name) {
  return "hello " + name;
}

Revised

function greet(name) {
  return `hello ${name}`;
}

0 added · 0 removed

How to use

Paste the original text on the left and the revised text on the right.
Compare. Added lines are green; removed lines are red.
Very large files are rejected so the tab stays responsive.

Features

Line-based LCS diff, rendered as React nodes (no innerHTML).
Shows left/right line numbers.
Counts added and removed lines.
Caps input size so an in-browser matrix cannot freeze the page.
Local processing only.

Examples

A one-line change

left: hello world / right: hello there

FAQ

Is this a git diff?

It is a line diff, not a unified patch with hunks and indexes. It does not understand git, and it does not do a word-level or character-level diff in this version.

Will it merge the files?

No. It only shows what changed. There is no three-way merge.

Related tools

About this tool

A text diff is the fastest way to see what changed between two pastes — a config, a README, a log excerpt — without creating a branch.

Alphzen computes the longest common subsequence of lines in the browser. That is enough for review and honest about not being a merge tool.

Related: Regex Tester to find a pattern in one file, Word Counter if you only need length.