Text Diff Checker

See what changed between two versions of a text

Text Diff Checker lines up an original and an edited version and marks every line that was added or removed. Where a line was edited rather than replaced, the words that differ are highlighted, so one swapped word in a long paragraph stands out.

It’s a textual comparison: it shows which characters differ, not whether the meaning changed. Both texts are compared inside your browser tab and aren’t sent anywhere.

How to compare two texts

1. Paste the older version into Original text and the newer one into Changed text.
2. Tick Ignore upper/lower case or Ignore extra spaces if those differences don’t matter to you.
3. Click Compare. A summary counts the lines added, removed and unchanged, with the full comparison below it.
4. Tick Show only changed lines to fold matching lines away, and use Swap sides if the versions went into the wrong boxes.

Reading the comparison

• Two number columns: each line’s position in the original and in the changed text, so you can find it in either version.
• Minus and plus: a red line marked − exists only in the original; a green line marked + exists only in the changed text.
• Word highlights: on an edited line, a darker shade marks the words removed from the old line and the words added in the new one.
• Folded runs: with Show only changed lines ticked, each stretch of matching lines shrinks to a note such as “… 12 unchanged lines”.

When comparing two texts saves time

• Contract drafts: check exactly what the other side changed between two versions of an agreement or policy.
• Editing and proofreading: confirm that only the intended corrections went into an article or essay.
• Settings and data files: spot the one value that differs between two configs. Run JSON through the JSON Formatter first so each value sits on its own line.

How the comparison works

Lines first, then words

The tool uses the Myers diff algorithm, the method Git uses by default, to find a shortest set of added and removed lines that turns the original into the changed text. When a removed line and an added line at the same spot are still largely alike, they’re treated as one edited line and compared word by word; lines that were rewritten completely are shown whole, without word highlights.

What the ignore options do

Ignore upper/lower case treats “Apple” and “apple” as equal. Ignore extra spaces drops spaces and tabs at the start and end of each line and treats any run of spaces as one, so re-indented lines match. Neither option skips blank lines or line breaks, so a paragraph rewrapped onto different lines still shows as changed.

Text Diff Checker: common questions