Line by line, with a similarity score
Line-by-line differences between two texts with case and whitespace options, plus a similarity percentage.
Spotting the difference between two near-identical texts by eye is close to impossible, particularly with a config file, a contract or two drafts of the same email. A line comparison does it instantly and gives the line number of every change.
The case and whitespace options matter more than they look. If the files were edited in different tools, half the "differences" will be trailing spaces, and without ignoring them the output is useless.
What this calculator shows
- Every changed line with its number: minus for the old, plus for the new
- How many lines changed and how many matched
- A similarity percentage — the quick answer to "how different is it"
What to keep in mind
- Comparison is by line number rather than by content, so inserting a line at the top shifts everything and shows as a wholesale difference.
- Blank lines count like any other and affect the numbering.
FAQs
Why did inserting a line create so many differences?
Comparison is positional, so an insertion shifts every subsequent line. A full longest-common-subsequence algorithm smooths that out; this uses simple line pairing.
Should I ignore whitespace?
Usually yes. Editors treat trailing spaces differently, and leaving them in fills the output with noise.
How is similarity calculated?
The share of lines that matched exactly, out of the total. It does not weight how much a line changed — only whether it did.
Is my text uploaded?
No, the comparison happens in the browser. That matters when the texts are contract drafts or configurations with real hostnames.
Worked example
Two drafts
Input: Three lines, the second edited
Output: 1 changed line, 66.67% similar
Note: The change is shown as a pair: first the line as it was, then as it became. That makes the actual edit easy to see.