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Text Diff Checker

Paste two blocks of text and see exactly what changed — line-by-line, side-by-side or unified, with added and removed lines highlighted. Ignore whitespace or case to filter noise.

  • Runs in browser
  • No signup
  • No tracking
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How to use Text Diff Checker

  1. Paste the original text into the left pane.

  2. Paste the changed text into the right pane.

  3. Pick split or unified view.

  4. Toggle Ignore whitespace / case to filter noise.

When to use it

  • Reviewing copy or release-note changes before publishing.

  • Comparing two API responses to spot regressions.

  • Spotting drift between two config files or env snapshots.

  • Auditing redacted logs against originals.

What it fixes

  • Eyeballing two blocks of text and missing a single-character change.

  • Online diffs that paywall multi-line output or upload your text.

  • Switching to a terminal just to run `diff` on two snippets.

About Text Diff Checker

Comparing two versions of text is one of the most common dev tasks: log files, config snapshots, copy revisions, API responses. The classic Unix `diff` does it offline but isn't always handy when you're in a browser.

This tool implements line-by-line LCS diffing in JavaScript. Pick split view to see the two versions side-by-side or unified view to see a single chronological feed. Toggle Ignore whitespace and Ignore case to suppress superficial differences.

References: Wikipedia — Longest common subsequence · git diff

Frequently asked

  • How is the diff computed?

    It uses the classic longest common subsequence (LCS) algorithm on lines — the same family of algorithms `git diff` and `diff -u` use. Lines unique to the left are flagged as removed, lines unique to the right as added.

  • Does it diff word-by-word?

    This tool diffs line-by-line. For sub-line changes, use Ignore whitespace to soften noise from indentation differences.

  • Is my text sent anywhere?

    No. Everything runs in your browser. Paste anything — internal logs, snippets, copy — and nothing leaves the page.

  • Can it handle large files?

    LCS is O(n×m), so very large inputs slow down. For diffs over a few thousand lines, prefer command-line `diff`.

Discussion

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