Redline (Document Comparison)

What is a redline?

A redline is a version of a document that shows exactly what changed: added words are marked, often underlined or in color, and deleted words are shown struck through. The name comes from marking changes in red.

In contract work, "to redline" usually means to propose changes to a draft. You send the other side the contract with your edits marked, they reply with their own edits, and the redlines go back and forth until both sides agree. Word processors do this with features such as tracked changes or suggested edits.

A redline can also be made after the fact by comparing two finished versions of a document. This is sometimes called a comparison or a blackline. The tool lines up the old text and the new text and marks every difference. That is the kind of redline that matters when a vendor updates its terms.

Two kinds of redline

Negotiation redline. Used when you are agreeing a contract, such as an MSA or a DPA. Both sides see and approve every change before signing.

Comparison redline. Used when one side changed a document on its own, such as a vendor updating its online terms of service. Nobody marked the edits, so you build the redline yourself by comparing the old version with the new one.

How to make a comparison redline

1. Get the old version. Use a copy you saved, an archived version the vendor offers, or a snapshot from a public web archive.
2. Get the new version from the live page.
3. Paste both into a document comparison tool, such as the compare feature in your word processor or a text diff tool.
4. Read every marked change, including small ones like "may" becoming "will" or a deleted "not".
5. Write a short note on what each change means for you.

Some vendors make this easier. GitHub keeps its site policies in a public repository, where policy updates are posted, and its terms point readers there to "view all changes to these Terms" (GitHub Terms). Google offers access to archived versions of its privacy policy (Google Privacy Policy). Not every vendor offers either one.

What it looks like in a vendor's terms

Negotiated contracts often say that only a signed change counts. A typical clause reads like this:

This Agreement may be amended only by a written document signed by authorized representatives of both parties.

• Amended only by a written document means redlines are proposals until they become a signed amendment or a signed final version.
• Signed by both parties means neither side can change the deal alone.

Online terms often work the other way. HubSpot's customer terms say "We may modify any part or all of the Agreement" and post the revised version online (HubSpot Customer Terms, section 12.1). With a unilateral amendment clause like that, nobody sends you a redline. If you want one, you make it.

A real change we caught

Venpo flagged the sentence GitBook deleted from its AI policy. GitBook's old policy promised "Customer data is never shared with OpenAI or used to train any AI models." The August 2026 replacement keeps a no-training promise but describes sending content to OpenAI. A deleted sentence leaves no trace on the new page. Only a comparison redline, with the old text struck through, shows that something is gone.

Why it matters to you

Long legal documents change in small places. One removed word can turn a promise into an option. A new sentence can add a fee. Reading the new version alone rarely shows this, because you do not know what used to be there.

A redline gives you proof. If a vendor's change affects a promise you made to your own customers, or you want to object within a notice window, a dated redline shows what changed and when. It is also useful in renewal talks, when you want to ask for the old wording back.

Redlines have limits. They show what changed in the text, not what it means. A tool will mark a fixed typo and a removed liability cap the same way. You still need to judge each change, which is where change severity comes in.

What to check

• Save a dated copy of each key vendor document now, so you have a baseline to compare against.
• When a "last updated" date changes, make a comparison redline before you read the new version.
• Look closely at small words: may, will, must, not, only, including, sole discretion.
• Check linked pages too. A change to a policy pulled in by incorporation by reference can change your contract.
• In negotiations, confirm the signed version matches the last agreed redline, word for word.

How Venpo helps

When a vendor's terms, privacy policy, DPA or subprocessor list changes, Venpo emails you a plain-English summary of what changed and why it matters, and keeps a change history for each vendor so you can see the old and new wording over time.