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Text Diff Checker

The comparison runs in your browser. Your texts are never uploaded.

Original text
Changed text
+4−3
1{1{
2 "name": "nicetool",2 "name": "nicetool.dev",
3 "version": "1.0.0",3 "version": "1.1.0",
4 "private": true,4 "private": true,
5 "scripts": {5 "scripts": {
6 "dev": "next dev"6 "dev": "next dev",
7 "build": "next build"
7 }8 }
8}9}

What is a diff checker?

A diff checker compares two versions of a text and shows exactly what changed. It is useful for reviewing config changes, comparing API responses, proofreading documents or checking code before a commit.

Features

  • • Side-by-side and unified views
  • • Word-level highlighting inside changed lines
  • • Ignore whitespace and letter case options
  • • Copy the result as a unified diff

Safe for sensitive data

Both texts are compared locally with JavaScript. Nothing is transmitted, so you can safely compare configs, logs and private code.

No upload, no storage.

How to use the Text Diff

  1. 1

    Paste the original version on the left and the changed version on the right.

  2. 2

    Differences appear instantly: removed lines in red, added lines in green, and the changed words inside a line are highlighted.

  3. 3

    Switch between side-by-side and unified view, and turn on Ignore whitespace or Ignore case when only real content changes matter.

  4. 4

    Use Swap texts to reverse the comparison, or Copy diff to paste the result into a ticket, a code review or an email.

Practical examples

Config drift

Compare the nginx.conf or .env file from staging with production to find the one setting that makes the two environments behave differently.

Contract and document changes

Paste two versions of a contract, policy or translation to see exactly which sentences were edited before you sign or approve.

API response changes

Compare a formatted JSON response before and after a deployment to spot renamed fields or changed values that break a client.

Reviewing generated text

Check what an editor, a translator or a formatting tool changed in your article instead of rereading the whole text.

Frequently asked questions

How does the comparison work?+

The tool uses a longest common subsequence algorithm, the same idea behind git diff, to find the smallest set of lines added and removed. Changed lines are then compared word by word.

What does Ignore whitespace do?+

It treats lines that differ only in spaces, tabs or indentation as equal. This is useful when one version was reformatted or uses different indentation.

Side-by-side or unified view?+

Side-by-side is easier to read for prose and small edits. Unified shows one column with - and + markers, the format used in patches and pull requests, and works better on narrow screens.

Are my texts uploaded?+

No. The comparison runs in your browser, so confidential contracts, code or customer data never leave your device.