How to flatten a PDF on Mac
The right move for a final, signed, archival copy — and the wrong one for a document you will keep working on.
Annotations sit on top of a page as objects. That is what makes them useful while a document is being worked on, and what makes them a liability once it is finished: whoever you send it to can move your highlights, delete your signature, or drag a stamp somewhere it does not belong.
Flattening ends that. The marks stop being objects and become part of the page.
Flattening is free and always will be. There is nothing to sign up for and nothing is watermarked.
Flatten, step by step
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Finish the document first
Flattening is a last step. Anything you want to change afterwards has to be changed before.
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Keep the unflattened original
Save a copy, or take a snapshot. This is the step people skip and regret.
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Open Flatten PDF
From the document actions panel, under Pages. Verso tells you what flattening will do before it does it.
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Check the result
Look at the pages that had marks on them. Try selecting text on one — on a flattened page, you will not be able to.
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Save the flattened copy
Under a new name, so the working version survives.
What flattening costs
Affected pages stop being text and become images. Their words can no longer be selected, searched, copied or edited, and a screen reader gets nothing from them. That is the trade: permanence in exchange for everything that depends on a page containing text.
| Before flattening | After |
|---|---|
| Marks can be moved and deleted | Marks are part of the page |
| Page text is selectable and searchable | Affected pages are pictures |
| Text can be edited in place | Nothing to click into |
| A screen reader can read the page | Nothing for it to read |
| File size is modest | Usually larger, because images are bigger than text |
When it is right
- A signed copy. A signature that can be dragged off the page is not much of a signature.
- An archival record. A document going into a file where it must never change again.
- A completed form being returned. So the answers cannot be altered after it leaves you.
- A stamped approval. “Approved” means less if the recipient can move it onto a different page.
When it is wrong
- A document still under review. You are destroying the ability to respond to the marks.
- Anything that must stay searchable. Including anything going into a system that indexes contents.
- Anything that must remain accessible. A flattened page fails an accessibility check for the most basic reason there is: it contains no text.
- As a substitute for redaction. Flattening a black rectangle makes the rectangle permanent; whether the text underneath survives is not something to gamble a confidential document on. Redaction removes content, and that is what it is for.
The alternative most people actually want
If the goal is “nobody should change this”, password protection is often the better answer: it restricts what can be done with the document while leaving the text intact and searchable. Flattening is for when the marks specifically must become part of the page.
Frequently asked questions
What does flattening a PDF do?
It fixes annotations permanently into the page, so they can no longer be moved or removed. The affected pages become pictures.
Does flattening make a PDF uneditable?
It makes the affected pages pictures, so their text cannot be selected, searched or edited. If the goal is to restrict what can be done with the document, password protection is usually a better fit.
Can I unflatten a PDF?
No. That is the point of it. Keep the unflattened original — save a copy or take a snapshot before you flatten.
Is flattening the same as redacting?
No. Flattening makes marks permanent. Redaction removes content. Flattening a black rectangle is not a safe way to hide what is underneath it.
Will flattening make my file bigger?
Usually, because images take more room than text. Compressing afterwards brings it back down.
Is flattening free?
Yes, along with the rest of the page operations.