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TabBench

Text Diff Checker

Compare two text snippets side-by-side to highlight additions, deletions, and line-by-line differences.

Runs in your browser. Nothing you add is uploaded.

What the Text Diff Checker does

Spotting what changed between two versions of a document by reading both is unreliable — the eye skips over single-word edits and transposed lines. A diff compares them mechanically and highlights every addition, deletion, and modification. This checker runs the comparison in your browser, which makes it usable for contracts, drafts, and code you would not paste into an online service.

How to compare two texts

  1. Paste the original version into the left panel.
  2. Paste the revised version into the right panel.
  3. Read the highlighted result — additions and deletions are marked distinctly.
  4. Switch between side-by-side and unified views depending on whether you want context or compactness.

The Text Diff Checker runs entirely in your browser — nothing you enter is uploaded, stored, or logged.

When to use it

Reviewing contract revisions

When a counterparty returns a document without tracked changes, a diff is the only reliable way to find what they altered.

Comparing configuration files

A single differing line between a working and a failing environment config is usually the whole explanation for an outage.

Checking edits to a draft

Comparing your draft against an editor's returned version shows precisely which changes were made rather than which were described.

Good to know

  • Diffs are line-based by default, so reflowing a paragraph marks the whole paragraph as changed even if one word moved.
  • Normalise line endings before comparing. A file saved on Windows and another on macOS can show every line as different purely because of CRLF versus LF.
  • Trailing whitespace produces differences that are invisible on screen — enable whitespace-insensitive comparison if that noise dominates.
  • For prose, word-level diffing is far more readable than line-level.

Frequently asked questions

How does the diff algorithm work?

It uses the Myers difference algorithm — the one behind git diff — to find the smallest set of added and removed lines. Lines that were edited rather than wholly added or removed are shown side by side with the changed words highlighted.

Why is the entire paragraph marked as changed when I edited one word?

Because line-based diffing treats a line as the unit of comparison, and an unwrapped paragraph is a single very long line. Any change within it marks the whole line. Word-level diffing gives much better results for prose; line-level is the right choice for code and configuration.

Is my text uploaded for comparison?

No. The comparison algorithm runs in your browser and neither version is transmitted. That is what makes this appropriate for unpublished drafts, legal documents, and proprietary code.

Can I compare files rather than pasted text?

Paste the contents of each file into the two panels. Binary formats such as .docx or .pdf will not compare usefully as raw text — extract the plain text first, then diff that.

What is the difference between side-by-side and unified view?

Side-by-side shows both versions in parallel columns, which makes it easy to see what a line became. Unified shows one stream with additions and deletions interleaved, which is more compact and is the format used by version control tools.

Why do two identical-looking texts show differences?

Almost always invisible characters: trailing spaces, tab-versus-space indentation, differing line endings, or a non-breaking space that looks exactly like a normal one. Enabling whitespace-insensitive comparison usually confirms this immediately.

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