Flatten PDF
Lock filled form fields and comments into the page. Runs on your device, nothing is uploaded.
How to use Flatten PDF
- 01Drop a PDF onto the upload area. The tool counts its form fields and comments.
- 02Choose Forms and comments to lock answers and marks, or Whole pages as images to lock everything.
- 03Click Flatten and download.
A filled-in PDF form still has live fields: anyone who opens it can change your answers, and some portals and printers drop the answers entirely. Flattening turns each answer, checkbox, highlight and stamp into ordinary page content, so the file looks the same everywhere and can't be edited by accident.
Forms and comments flattening keeps the page as it is and only fixes the interactive layers in place, so text stays sharp and searchable. Comment bubbles are removed, links keep working. It runs in your browser with pdf-lib; nothing is uploaded.
Whole pages as images goes further: every page is redrawn as a picture at about 200 dpi, so nothing at all can be selected, copied or edited. The file gets bigger and text is a little softer, so use it only when you need a fully locked copy.
Questions
Is my PDF uploaded?
No. Flattening happens inside your browser tab and nothing is sent to a server.
Why flatten a filled form before sending it?
So your answers can't be changed and show up in every viewer and printer. Some upload portals lose unflattened answers.
Can flattening be undone?
No. Keep your original if you might need to edit the answers again.
Does it make the PDF secure?
It stops casual editing. To stop people opening the file, add a password with Protect PDF.
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