Text Diff Checker

Compare two pieces of text side by side and see what was added, removed, or changed.

Ignore case Ignore whitespace

Original

Hello world
This is line two
This is line three

Modified

Hello there
This is line two
This is the new line three

Diff result

Features

Side-by-side view

Color-coded diffs

Inline diff marks

Ignore whitespace option

How to Use

1. Paste the original text into the left panel.

2. Paste the modified text into the right panel.

3. Differences are highlighted automatically: green for added, red for removed.

About this tool

When two versions of a document, config file or list look almost the same, finding what changed by eye is slow and unreliable. This checker compares the texts line by line using a longest-common-subsequence algorithm — the same idea behind diff and version-control tools — and shows unchanged lines alongside additions in green and deletions in red, with a summary count of each. Options to ignore letter case or whitespace help when only formatting differs, for example after re-indenting code or normalising capitalisation. It is useful for reviewing contract edits, comparing configuration between environments, checking translations against a source, or spotting what a colleague changed in a pasted snippet.

Frequently Asked Questions

How does the comparison work?

The tool finds the longest sequence of lines that appear in both texts in the same order, then marks every other line in the original as removed and every other line in the new text as added. This is the classic approach used by diff utilities.

Why is a small change inside a line shown as a removed and an added line?

The comparison works at line level, so any edit within a line replaces the whole line. Look at the red and green pair next to each other to spot the exact characters that changed.

What do "Ignore case" and "Ignore whitespace" do?

They make the comparison treat lines as equal when they differ only in capital letters or in spaces and tabs. This hides formatting noise so real content changes stand out.

Can I compare two files or Word documents?

Paste the text content into the two boxes. For Word or PDF files, copy the text out first; formatting such as bold or tables is not compared, only the characters.

Is there a limit to how much text I can compare?

Comparison runs in your browser and its work grows with the number of lines in both texts, so a few thousand lines are fine. For very large files, a command-line diff or your code editor will be faster.