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Flatten PDF

Merge form fields and annotations into the page so they cannot be edited.

Your files never leave your device.

When to use it

Flatten PDF makes the contents of a PDF permanent. Filled-in form answers, comments, stamps, signatures and other interactive layers are merged into the page so they can’t be changed or lost, and they look the same in every PDF reader. Use it before submitting a completed form, sending a signed contract, archiving a document, or printing a file whose annotations don’t show in some apps.

How to flatten a PDF

  1. Tap Choose PDF file, or drag a PDF onto the box.
  2. Under What should be flattened?, choose:
    • Form fields: filled-in fields become normal page content. Text stays sharp and searchable.
    • Everything: fields, comments, stamps and signatures are merged into page images. Text can no longer be selected.
  3. Press Flatten PDF, then Download. The file ends in “-flattened.pdf”.

A worked example

You’ve completed a 4-page rental application with typed answers and want to email it to a landlord. Some PDF apps on phones don’t show form answers properly, and anyone could edit them. Choose Form fields and press Flatten PDF. The answers become part of the pages, look identical on every device, and can’t be changed by accident. The text is still searchable, so the landlord can find your details quickly.

When to choose “Everything”

  • Sticky notes and markups from a review that must appear when printed.
  • Stamps and drawn signatures added as annotations.
  • Documents for archiving where nothing should be editable.
  • After cropping, to remove the content hidden outside the new page edges.

Why some apps don’t show annotations

Comments, highlights and form answers live in separate layers on top of the page. Some phone viewers, email previews and older printers ignore those layers, so the recipient sees a blank form or no comments at all. Flattening moves everything onto the page itself, which every viewer shows.

Tips

  • Flatten the final version only; keep an editable copy for corrections.
  • Use “Form fields” when possible, so text stays selectable and the file stays small.
  • Check the result in your normal PDF reader before sending.
  • Compress afterwards if “Everything” made the file large.

Common mistakes

  • Flattening before checking answers, then needing to retype the form.
  • Choosing “Everything” for a long text document, which makes it larger and unsearchable.
  • Assuming flattening adds security. For confidentiality, use Protect PDF.
  • Flattening a locked PDF. Unlock it first.

Private by design

Your PDF is processed in your browser and never uploaded.

Fill the form first with Fill PDF Form, sign it with Sign PDF, or reduce the size with Compress PDF.

Frequently asked questions

Which option should I choose?

Choose "Form fields" to lock filled-in answers while keeping the text sharp and searchable; it suits completed applications and contracts. Choose "Everything" when comments, stamps, signatures or hidden content must be merged permanently, accepting that text becomes part of an image.

Why can't I select text after flattening "Everything"?

That option turns each page into a high-quality image (about 200 DPI), which is what makes everything permanent. Keep an unflattened copy if you'll need to copy text later.

Does flattening make the file bigger?

"Form fields" usually keeps it about the same size. "Everything" can make text-heavy documents larger, because each page becomes an image. Compress PDF can help afterwards.

Can someone undo flattening?

Not easily. Flattened answers are no longer form fields, so they can't simply be edited in a form. That's the point, but it also means you should flatten only the final version.

Is my document uploaded?

No. Flattening happens in your browser.

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