Text Diff Checker

The Text Diff Checker compares two texts side-by-side using a longest common subsequence (LCS) algorithm to detect differences at both word and character levels. It highlights additions in green and deletions in red, updating in real-time as you type. All processing happens entirely in your browser — nothing is sent to any server.

Word-level diff compares text word by word, which is ideal for comparing sentences and paragraphs — it shows which words were added, removed, or changed. Character-level diff compares individual characters, making it useful for spotting small changes in code, URLs, or closely related text strings. You can switch between modes using the dropdown above the input panels.

Absolutely. 🔒 Your text never leaves your device. The entire diff comparison is computed locally in your browser using client-side JavaScript. There are no server calls, no data storage, and no tracking of your content. This tool is 100% private by design.

When enabled, the Ignore Whitespace option normalizes all whitespace within each line (collapsing spaces and tabs) before comparing. This is useful when you want to compare content differences without being distracted by formatting changes, indentation differences, or trailing spaces. Line structure (newlines) is preserved. The original text display is unaffected.

The statistics panel shows: Insertions (+) — lines or segments added in the modified text, highlighted in green. Deletions (−) — lines or segments removed from the original, highlighted in red. Unchanged — lines that are identical in both texts (shown in amber). Changed (%) — percentage of lines that differ, indicating the overall variation between the two texts.

Yes! Click the 📋 Copy Diff button in the controls bar. It copies a unified diff format (similar to git diff) to your clipboard, which you can paste into emails, documents, code reviews, or messages. A toast notification will confirm the copy was successful.