Edit Diff Summary AI & Writing
Compare a draft with its rewrite and see exactly what changed, word by word.
Edit Diff Summary is a free online tool that compare a draft with its rewrite and see exactly what changed, word by word. It runs entirely in your web browser using plain JavaScript, so files are processed on your own device and never uploaded to a server. There is no sign-up, no file size limit imposed by the site, no watermark and no paid tier.
- Price
- Free — no account, no quota, no watermark
- Category
- AI & Writing
- Where it runs
- In your browser, on your device
- Files uploaded
- None
- Technology
- plain JavaScript
- Settings
- 3
- Works offline
- Yes, after the first visit
About Edit Diff Summary
A line diff on prose is close to useless. Change one word in a paragraph and reflow it, and every line reads as modified — technically true and completely uninformative. This diffs by word using a longest-common-subsequence match, so an edited paragraph shows exactly the words that moved and leaves the rest alone.
How to use it
- Paste the text you want to run through edit diff summary.
- Set rewritten version, show as and ignore case.
The 3 settings
| Setting | What it does | Default |
|---|---|---|
| Rewritten version | Free text. | The quick red fox leaps over the lazy dog and then sprints away quickly. |
| Show as | Choose from 2: [-removed-] {+added+}, A list of changes. | [-removed-] {+added+} |
| Ignore case | On or off. Off by default. | Off |
Under the hood
| Runs on | plain JavaScript — runs the whole thing |
| Controls | Rewritten version, Show as, Ignore case |
Questions
Why is it limited to a few hundred words a side?
The comparison builds a table of every word in one version against every word in the other, so the work grows with the product of the two lengths. A few hundred words each is instant; a whole chapter would lock the tab. Compare a section at a time.
What does the similarity percentage mean?
The share of the original text that survived unchanged. A light edit lands above 90%; a genuine rewrite is usually below 50%. It is a rough measure of edit distance, not a plagiarism score.
Can I use this to check what an AI changed in my draft?
That is exactly what it is good at. Paste your original above and the returned version below, and the word-level marks show every substitution — including the small ones that are easy to accept without noticing, like a hedge added to a definite statement.