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TNToolsNexus

Text diff checker

Compare two texts line by line — additions and removals highlighted with line numbers, counts, and an identical verdict. Free, private.

Both texts stay in your browser — the comparison runs on your device.

Paste two versions and see exactly what changed: unchanged lines anchor the view, additions glow green with a +, removals red with a −, each carrying its original line number — or a plain “identical” verdict when nothing differs.

How to compare two texts

  1. Paste the original on the left, the changed version on the right.
  2. Read the counts (+added / −removed) and scroll the highlighted result.
  3. Line numbers on both sides tell you where each change lives in each version.

Where a diff beats squinting

Two versions of a contract back from the other side — did anything change besides the date? A config file that works on one server and not the other. An edited paragraph a collaborator “only touched slightly”. A generated file that should match yesterday’s. Reading both versions side by side catches perhaps half of real changes; a diff catches all of them, mechanically, including the invisible ones (a trailing space, a swapped comma) that eyes skate over.

Reading the output like a developer

The algorithm finds the longest thread of unchanged lines and pins the differences around it — so a paragraph moved intact shows as removed-here, added-there rather than fifty spurious edits. An edited line appears as its old version (−) directly above its new version (+): both visible, nothing summarized away. Exactness is deliberate: whitespace differences are real differences in configs and code. Need looser matching? Normalize both sides first with the case converter or line-break remover, then diff.

Private by design

The documents people diff — contracts, offers, configs with secrets — are exactly the ones that shouldn’t visit a server. Both sides stay on your device, and nothing is retained.

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Frequently asked questions

How does the comparison work?
Line by line, using the longest-common-subsequence algorithm — the same family of logic behind git diff. Unchanged lines anchor the comparison; everything else shows as added (green, +) or removed (red, −) with line numbers from each side.
Why does an edited line show as one removal plus one addition?
Because at line granularity that's what an edit is: the old line left, a new line arrived. This matches how developers read diffs; it also means nothing is ever silently merged — you see exactly both versions of the changed line.
Does it ignore whitespace or case?
No — lines must match exactly, which is usually what you want when checking contracts or configs (a changed space in YAML is a real change). Normalize first if you need looser matching: the case converter and line-break tools sit one click away.
Is there a size limit?
Five thousand lines per side — far beyond any pasted document, and the guard keeps the comparison instant. Windows/Unix line endings are treated as equal.
Are my documents uploaded to compare them?
No. Both texts stay in your browser; the algorithm runs on your device — which matters, because diffed documents are usually contracts and internal drafts.

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