Text Compare & Diff Checker
Paste two versions of a text and see precisely what changed – added lines highlighted in green, removed lines in red, unchanged lines in grey – with counts and a similarity percentage.
Useful for comparing document drafts, checking what an editor changed, spotting differences between two config files, or verifying that a copy-paste really is identical.
How to use the text compare & diff checker
Paste the original text into the first box.
Paste the changed version into the second.
Click Compare to see the highlighted differences.
Why use the Convert Now text compare & diff checker
Line-by-line diff
Colour-coded additions and removals, like a code review.
Similarity score
Instant sense of how much actually changed.
Handles insertions well
Uses a proper LCS algorithm, not a naive line match.
Private
Confidential drafts never leave your browser.
How the comparison works
The tool uses a longest common subsequence algorithm – the same approach behind the diff command and version control systems. Rather than comparing line one to line one, it finds the largest set of lines that appear in the same order in both texts, and treats everything else as an insertion or deletion. That is why inserting a paragraph at the top does not mark the entire rest of the document as changed, which is what a naive line-by-line comparison would do.
Reading a diff
Lines marked with a minus exist only in the original; lines marked with a plus exist only in the new version. A modified line usually appears as both – the old version removed and the new one added – because at line granularity, a change is a deletion plus an insertion. The similarity percentage tells you at a glance whether you are looking at a light edit or a rewrite.
When comparison is not enough
A diff shows what changed, not whether the change was correct. It also cannot detect reordering as a move – shifting a paragraph shows as a deletion in one place and an addition in another. For prose, read the changed lines in context rather than trusting the count alone.
Read the guide: How to Calculate Percentage: Formulas & Examples
Frequently asked questions
How do I compare two texts?
Paste the original into the left box and the revised version into the right, then click Compare.
What do the colours mean?
Green lines with a plus were added, red lines with a minus were removed, and grey lines are unchanged.
Can I compare documents from Word?
Yes – copy the text and paste it in. Formatting is not compared, only the text itself.
Does it detect moved paragraphs?
It shows them as a removal in one place and an addition in another, since line-level diffs do not track moves.
Is my text uploaded to a server?
No. The comparison runs entirely in your browser, so confidential documents stay private.
Is there a size limit?
Very large texts (many thousands of lines) may be slow, as the comparison is quadratic in document length.
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