What Is Contract Redline Tool?
Contract Redline Tool compares two versions of a contract or legal document and highlights every change — additions, deletions, and modifications. It’s the standard workflow for negotiating agreements, reviewing edits from opposing counsel, and tracking revisions across contract drafts.
How to Use This Tool
Paste or upload the original contract and the revised version. The tool performs a detailed text comparison and generates a redline view showing insertions in green, deletions in red with strikethrough, and moved text. You can navigate between changes and export the redlined document. All comparison happens in your browser — your contract text never leaves your device.
Why Use Contract Redline Tool?
Professional redlining tools are built into expensive legal software suites. This tool provides the same visual diff for free, with the critical advantage that sensitive contract language is never uploaded to any server. It’s ideal for freelancers, small businesses, and anyone reviewing agreement changes. For a detailed walkthrough, see our step-by-step guide.
Frequently Asked Questions
How is this different from Word's Track Changes?+
Word's Track Changes requires both parties to be using Word and to have kept change tracking enabled throughout every edit. If a collaborator edits without it on, accepts all changes, or sends you a fresh PDF, the audit trail is lost. Contract Redline works on final artifacts — drop in any two versions of a contract (even as PDFs after a round trip through signing software) and we reconstruct the redline from the actual text.
Does it work on PDFs or only Word files?+
Both. Drop PDF or DOCX files in either slot, and you can mix — compare a PDF against a Word doc, or two PDFs against each other. We extract text via pdf.js for PDFs and mammoth for DOCX, then run the diff on the extracted text.
Will it detect moved paragraphs?+
Moved paragraphs show as a deletion in one place and an insertion in another — the diff algorithm is line-by-line so a paragraph moved from page 2 to page 5 appears as two entries. This matches how DocuSign Rooms and most contract-review tools handle moves. If move-detection is critical, combining the redline with the original document layout (via side-by-side reading) usually makes the intent obvious.
Is my contract uploaded to a server?+
No. Both files are parsed locally in your browser. pdf.js handles PDF text extraction entirely client-side; mammoth does the same for DOCX; the diff runs in-browser JavaScript. No uploads, no server side processing, no record kept of your document contents. This matters especially for contracts containing sensitive commercial terms.
Does it handle scanned contracts (images of text)?+
Not directly — the tool extracts the PDF's text layer, which scanned PDFs don't have. First run your scanned PDF through our PDF OCR tool to generate a searchable text layer, then feed the OCR'd result into Contract Redline. Note that OCR errors can introduce false differences between the two compared files, so review the OCR output before comparing.
Can I export the redline?+
Yes. Export as an HTML file that preserves the red/green highlighting — you can open it in a browser, email it, print to PDF, or share as-is. The output is styled for screen and print, and keeps the insertions/deletions/unchanged formatting so a reviewer can scan through quickly.
Does the tool replace having a lawyer review the contract?+
No. The tool produces a redlined comparison and flags clauses that commonly cause issues, but no automated tool can replace a lawyer evaluating the specific deal in context. For any contract over a meaningful amount of money, any contract that grants rights to your IP or your data, or any contract that limits your ability to compete or work, have a licensed attorney in your jurisdiction review the final text before signing.
Are the contracts I paste analyzed in my browser or sent to a server?+
The diff and redline analysis runs entirely in your browser. Contract text never leaves your device. This matters because contracts often contain confidential commercial terms, party names, and pricing that should not be exposed to third-party servers. The optional clause-explanation feature (which uses pattern matching on common contract language) also runs locally; no AI API is called.
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