How to Compare Two Texts and Spot Every Difference

What diffing does

The tool treats each input as a list of lines and runs a line-by-line comparison. Lines present in the new version but not the old are marked as additions; lines present in the old but not the new are marked as deletions; lines that appear in both are unchanged. The result is a colour-coded view that lets you scan the changes at a glance.

Diffing operates on whole lines by default. A line counts as changed if any character within it differs, even a single space — which is why cleaning both versions first matters so much.

How to compare drafts

A reliable review workflow:

• Paste the older version on the left (or in the "original" field) and the newer version on the right (or in the "revised" field). Direction matters: additions and deletions are reported relative to the original.
• Clean both versions first. Run the Text Cleaner on each so whitespace-only differences do not clutter the diff with false changes.
• Scan the additions and deletions together. A deleted line followed by an added line is usually a rewrite; a lone addition or deletion is an insert or remove.
• Re-diff after edits. Once you accept or reject a change and produce a new version, diff again to confirm the result matches your intent.

When to diff text

Diffing is the right tool whenever you have two versions and want to know exactly what changed: comparing a collaborator’s edit to your original, checking a contractor’s revision against the brief, verifying that a copy-paste preserved a document, or reviewing your own edits between drafts. After spotting the differences, use Find & Replace to apply a change across the whole document, or the Text Cleaner to tidy both versions before comparing again.