Text Diff Checker

How it works

Paste your original text on the left and the changed version on the right. This tool compares them directly in your browser using jsdiff, a well-tested diffing library, and highlights every difference line by line: removed lines in red, added lines in green, changed words marked inside them. Nothing is uploaded — the entire comparison happens client-side.

Every line gets its own row with line numbers and a −/+ marker in the gutter: removed lines have a red background, added lines green, unchanged lines stay plain — and long unchanged stretches collapse into a "show N unchanged lines" button so only the differences demand attention. When a line was modified rather than fully replaced, the exact changed words inside it are additionally highlighted with a darker marker, so "14 days" versus "30 days" is visible at a glance. Switch between the unified single-column view (familiar from code reviews) and the side-by-side view with the original on the left and the changed version on the right.

Useful for reviewing edits to a document, comparing two versions of a config file, spotting what changed between two API responses, or checking a translation against its source without needing a code editor's diff view.

Limitations

This tool compares exactly two texts at once — there's no three-way merge or multi-file comparison. Very large inputs (megabytes of text) may take a moment to compute since the diffing algorithm runs in your browser's main thread.

FAQ

Is this text diff tool really free?

Yes — completely free, with no limits and no account required. The comparison runs entirely in your browser.

What's the difference between the unified and side-by-side views?

Unified shows one column with removed lines (−, red) directly above their replacements (+, green) — compact and familiar from code reviews. Side by side puts the original on the left and the changed version on the right, aligned line to line — easier for prose and long documents. In both views the exact changed words inside a modified line are additionally highlighted with a darker marker.

What do the line numbers in the gutter mean?

The first column is the line number in the original text, the second — in the changed text. A removed line has only the first number (it no longer exists in the new version), an added line only the second.

Is my text uploaded anywhere?

No — the comparison uses the jsdiff library running locally in your browser. Neither text is ever sent over the network, so it's safe to compare sensitive documents, contracts, or code.

Can it compare more than two pieces of text?

Not right now — this tool compares exactly two texts (original vs. changed) at a time. For comparing more, run it pairwise.