About this tool
Why it exists.
Between the first draft and the final one, small changes disappear. A line-by-line diff makes them visible again. Paste the original on the left and the revision on the right to see what was added, removed and left alone.
The comparison runs locally using a longest-common-subsequence pass. It is designed for readable prose, notes and configuration snippets. Very large documents are capped to keep the browser responsive; compare them in sections if needed.
How to use it.
- Paste the original text on the left and the new version on the right.
- Adjust the ignore-case and ignore-whitespace options if needed.
- Read the highlighted result and copy a summary of the changes.
Good questions.
Is this a character-level diff?
It compares whole lines and highlights added or removed lines. That makes prose and code review easier to scan than a dense character-level diff, though small edits inside a changed line appear as a full-line change.
How much text can I compare?
The tool caps input at roughly 2,000 lines per side and 300,000 characters total to avoid freezing a browser tab. For larger files, compare one chapter or one configuration block at a time.
Does any text leave my browser?
No. The diff is calculated in the page. There are no uploads and no server-side copy of either version.