Redline Generator
Compare two versions of a text and see every edit marked up, word by word.
Original text
Revised text
Redline
Paste two versions of a text above — deletions show struck through in red, additions underlined in green.
A redline marks every difference between two versions of a document: text that was removed is struck through, text that was added is underlined. The comparison here works word by word and runs entirely in your browser, so neither version is uploaded anywhere.
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- Word-level
- Uploads
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Related tools
A redline shows what changed between two versions of a document. Deleted words are struck through in red and new words are underlined in green. Lawyers redline contracts, editors redline drafts, and teams redline web copy before it ships.
Paste the earlier version in the left box and the newer version in the right box. The redline updates as you type, and Copy redline puts the marked-up result on your clipboard, ready to paste into Word, Google Docs, or an email.
This redline generator compares the two texts in your browser. Neither version is uploaded, logged, or sent to a server, which matters when the document is a contract, an offer letter, or anything else you'd rather keep private.
What is a redline?
A redline (also called a blackline or a comparison document) is a copy of a document with every edit marked. Removed text is struck through and added text is underlined. The name comes from lawyers marking contract changes by hand in red ink.
It saves you from taking someone's word for what they changed. Typical cases:
- Contracts: confirm the other party changed only what they said they changed.
- Editing: show an author exactly what a proofreader or editor touched.
- Web copy and documentation: review wording changes before they go live.
- Papers and reports: see what a co-author rewrote between drafts.
How to use the redline generator
- Paste the earlier version into the Original text box.
- Paste the newer version into the Revised text box.
- Read the redline below: red strikethrough means deleted, green underline means added. The label above it counts the words removed and added.
- Click Copy redline to paste the marked-up text into Word, Google Docs, or an email.
Example
Say a payment clause was edited between drafts:
- Original: "Party A shall pay within 30 days."
- Revised: "Party A shall pay within 45 days of receipt."
- Redline: "30" is struck out and "45" is underlined. Punctuation stays attached to the word next to it, so "days." is struck out and "days of receipt." is underlined as one change.
Is it safe to paste a contract here?
Yes. The comparison is ordinary JavaScript running on your own machine. Open your browser's network tab while you use it and you won't find a request carrying your text. There's no account to create, and closing the tab clears both boxes.
To be precise about tracking: the site runs Google Analytics and counts each time the redline updates, so we know the tool gets used. Neither of those includes a word of what you pasted.
Why use this redline generator?
- Free, with no sign-up.
- Your text stays in the browser. Nothing is uploaded.
- Word-level comparison, so a one-word edit in a long paragraph is marked as one word, not the whole paragraph.
- Copy redline keeps the strikethrough and underline when pasted into Word, Google Docs, or most email clients.
- Works on phones as well as desktops.
Frequently asked questions
What is a redline generator?
A tool that compares two versions of a text and produces a marked-up copy showing every change. Deletions are struck through and additions are underlined, the same convention lawyers use when marking up contracts.
Is this redline generator free?
Yes. There's no account and no paywall.
Does my text get uploaded anywhere?
No. The comparison runs in your browser using JavaScript. Neither version of your text is sent to a server, logged, or stored.
Can I paste the redline into Word or Google Docs?
Yes. The Copy redline button copies formatted text, so the strikethrough and underline survive when you paste into Word, Google Docs, or most email clients. Plain-text editors get [-removed-] and {+added+} markers instead.
What if the two versions are very different?
The word-by-word pass stops at about 1,500 edits, counting words and the spaces between them. Past that, the tool marks the whole changed stretch as one deletion followed by one addition. Matching text at the start and end still shows as unchanged.
How is this different from track changes in Word?
Track changes records edits as they are made. A redline generator compares two finished versions after the fact, which works even when the edits were made without track changes turned on.
Can it compare Word or PDF files?
Not directly. Copy the text out of the file and paste it in. The tool compares the words themselves and ignores fonts, tables, and layout.
Built and maintained by Bipul Kumar. Found a wrong number or a broken result? Tell me and I'll fix it.