Text Diff Checker

Compare two text snippets side-by-side and highlight the differences. Word- and line-level diff, everything runs in your browser.

Last updated: July 19, 2026

Original

function greet(name) {
  console.log("Hello, " + name);
  return name;
}

Modified

function greet(name, greeting = "Hello") {
  console.log(greeting + ", " + name + "!");
  return { name, greeting };
}

+ 3 added− 3 removed= 1 unchanged

1		−	function greet(name) {
2		−	console.log("Hello, " + name);
3		−	return name;
	1	+	function greet(name, greeting = "Hello") {
	2	+	console.log(greeting + ", " + name + "!");
	3	+	return { name, greeting };
4	4		}

Paste two blocks of text above to compare them side-by-side. Added, removed, and unchanged lines are highlighted, just like git diff. Everything runs in your browser.

What is Text Diff?

A text diff checker compares two versions of text and highlights exactly what changed — added lines in one color, removed lines in another. It's the same mechanism behind git diff and code-review tools. Beyond code, it's invaluable for comparing config files, contract revisions, log snapshots, and any two documents where you need to see precise differences fast.

How to compare two texts

1Paste the original text on one side and the revised text on the other.
2The tool aligns the two and highlights added, removed, and unchanged lines.
3Scroll through to review each change in context.
4Copy or note the differences for your review or changelog.

Use Cases

Compare config versions

Spot exactly what changed between two versions of an .env or config file.

Review text revisions

See edits between two drafts of documentation, a contract, or an email.

Diff log snapshots

Compare two log captures to find which lines appeared or disappeared between runs.

Code Examples

Diff view

  unchanged line
- old value
+ new value
  unchanged line

Key Concepts

Line-level vs word-level diff: Line-level marks whole lines as changed; word-level highlights the specific words within a line that differ. Line-level matches git's default.
Longest Common Subsequence (LCS): Most diff algorithms find the longest sequence of unchanged lines, then mark everything else as added or removed.
Whitespace sensitivity: By default, trailing spaces and line-ending differences (CRLF vs LF) can show as changes. Normalize input if that's noise.

Tips & Best Practices

▸Invisible differences (trailing spaces, CRLF vs LF line endings) often explain 'identical-looking' lines flagged as changed.
▸For code review, line-level diff matches what git and GitHub show.
▸Large inputs (multi-MB) can slow browser rendering; diff smaller sections when possible.
▸Sort or normalize both inputs first if order isn't meaningful, to reduce diff noise.

Frequently Asked Questions

Which diff granularity is used?

Line-level by default, showing added, removed, and unchanged lines. This matches how git diff and most code review tools present differences.

Are large files supported?

The tool runs entirely in the browser. Inputs up to a few megabytes work smoothly; much larger inputs may slow down rendering.

Text Diff Checker

What is Text Diff?

How to compare two texts

Use Cases

Compare config versions

Review text revisions

Diff log snapshots

Code Examples

Key Concepts

Tips & Best Practices

Frequently Asked Questions

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