Yes. You can redline a PDF by adding proposed edits—such as insertions, replacements, strikethroughs, highlights, underlines, and comments—without silently changing the text. If you have two versions and want to find what changed, use a file-comparison tool instead. Markup communicates suggestions; comparison detects differences.
What “redline a PDF” can mean
The term describes two related but different jobs. Choose based on what you have and what you need to tell the next reviewer:
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- Mark up one PDF to show suggested changes or explain a concern. The annotations indicate what a reviewer proposes; they do not automatically accept the edits or apply them to the underlying document.
- Compare two PDFs to locate differences between an older and a newer version. The comparison report shows changes to inspect; it does not decide whether a change is correct or important.
How to redline one PDF in Acrobat on the web
Adobe’s Acrobat web help, last updated September 1, 2026, describes tools to highlight, strike through, or underline selected text; insert text; replace selected text; add comments; and draw freehand. To suggest wording or flag a passage:
- Open the document in Acrobat on the web.
- Select the text or area you want to review.
- Choose a redlining tool from the context menu. For an insertion or replacement, you can also use Quick Actions: “Insert text” or “Replace selected text.”
- Enter the proposed wording when prompted. Add a comment from the comments pane if the markup needs an explanation.
- Check the placement and color of the annotations, then save or share the reviewed PDF as appropriate.
Use an insertion or replacement annotation to make a suggestion visible to the author. The documented workflow is for markup and comments, not automatic acceptance of every suggestion or a change to the source document’s underlying text. Adobe’s Acrobat web redlining guide lists the available actions and steps.
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How to compare two PDF versions in Acrobat Pro
When you have both an old and a new file, Acrobat Pro’s Compare Files feature can generate a report of their differences. Adobe’s help page, last updated February 26, 2026, documents this workflow:
- Open Acrobat and choose All tools > Compare files.
- Select the old and new files, or change the files already selected.
- Adjust the comparison settings for the type of document and the differences you want to display.
- Run the comparison. Acrobat presents the results in a new document.
- Review the changes in side-by-side or single-page view, navigate through the differences, and save the report if you need to keep or share it.
Comparison settings are not one-size-fits-all. Adobe describes options for reports, spreadsheets, and magazine layouts; presentation decks; and scanned documents, drawings, and illustrations. For scanned files, comparison works on page images and can match pages even when their order has changed. You can also choose text-only comparison and filter which differences appear. Inspect the actual documents: the report identifies differences but does not judge their meaning. Adobe’s Compare Files guide explains the workflow and settings.
Which workflow should you use?
- You are reviewing a single draft: Add markup when you need to propose replacement wording, indicate text to remove, highlight a passage, or explain a concern in a comment.
- You have two versions: Compare the files when you need to locate what changed, then review the report against the documents.
- The PDF is a scan, drawing, or layout-heavy file: For comparison, select settings suited to the document type; image-based comparison is relevant to scanned pages.
- You need a review record: Markup keeps suggestions and comments in the reviewed PDF. Comparison produces a separate report. These outputs serve different purposes.
Check feature availability before starting
The cited markup instructions cover Acrobat on the web, while Adobe documents Compare Files as a feature in Acrobat Pro. Availability can depend on platform and plan, so confirm that the feature you need is included in your setup before directing reviewers to a workflow. Adobe’s PDF annotation guide also describes annotating and sharing marked-up documents.
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