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What Flatten PDF does
Flatten PDF bakes editable content permanently into the page, either locking form fields while keeping text selectable, or redrawing every page as an image so nothing can be changed.
"Flatten" means two genuinely different things depending on why you are asking, so this tool offers both rather than guessing. If you have filled in a form and want to send it as final, you want the field values fused into the page so nobody can retype them — but you still want the text to be real text. That is "Form fields only".
If instead you need the file to look identical everywhere no matter how obscure the recipient's PDF reader is — with every highlight, stamp, annotation and layer welded in place — you want "Everything to images". Each page is re-drawn exactly as it appears and becomes a picture. It is the stronger guarantee, and you pay for it with selectable text and file size.
How to use Flatten PDF
Upload the PDF
Drop in the document you want to flatten.
Choose what to flatten
Pick "Form fields only" to keep text selectable, or "Everything to images" to bake in absolutely everything.
Flatten and download
Click Flatten PDF. The result downloads and the tool reports what it actually did.
Flatten PDF: details and limits
"Form fields only" reports how many fields it flattened. If your PDF has no form fields there is nothing to do and the copy is unchanged — a useful signal that you probably wanted the other mode.
"Everything to images" is the only mode that truly removes content hidden outside the visible page area, which makes it the right follow-up to cropping something sensitive.
Flattening to images makes text unselectable and unsearchable. It is a trade, not an upgrade.
"Everything to images" re-photographs each page at 144 DPI and stores it as a JPEG, so it is lossy: fine hairlines and small text soften slightly, and a page that was crisp vector art will not come back crisp. If the file must stay sharp for print, this is the wrong mode.
Pages wider than about 16 inches — A0 posters, large CAD sheets — are quietly rendered at a lower resolution to stay within a size ceiling. Ordinary A4 and Letter pages are never affected.
Flattening is permanent in the downloaded copy. Your original file stays editable, so keep it if the form may need changing later.
Flatten PDF: frequently asked questions
Guides
- How-to · 6 min
How to flatten a PDF
“Flatten” means two different things. Pick the wrong one and you either lose your text or fail to lock anything down.
- Article · 7 min
Why a PDF looks different on someone else’s screen
A PDF either carries its fonts or names them and hopes. Guess which one moves your line breaks.