PDF Medic OnlineFlatten PDF
Lock filled-in forms and comments into the page so they can no longer be changed.
Files never leave your device
How to Flatten PDF
- Choose a PDF, or drop it on the box above.
- Under “What to flatten”, pick “Forms and comments” or “Everything — pages become pictures”.
- Press Flatten PDF, then Download. You get a new file ending in “-flat”; your original is not changed.
What flattening means
A PDF can carry things that float above the page: form fields you type into, tick boxes, highlights, sticky notes, stamps and drawings. Any PDF reader can still change or delete them. Flattening writes them into the page itself, so they become part of the document like printed ink.
People flatten a file before sending a filled-in form, so the answers can no longer be typed over. It also helps when a phone viewer or a printer shows filled-in fields as empty: once the answers are part of the page, every viewer shows them.
The two ways to flatten
Forms and comments (text stays selectable). Form fields, tick boxes, comments and highlights are drawn into the page exactly as they look on screen. Things the reader hides stay hidden. Everything else is untouched: text stays sharp, selectable and searchable, and links keep working. This is the right choice for most forms.
Everything — pages become pictures. Each page, with its fields and comments, is drawn as a high-quality picture (220 dots per inch) and the file is rebuilt from those pictures. Nothing can be selected, copied or edited afterwards. Links, bookmarks and selectable text are gone, and screen readers can no longer read the page. The file may get bigger, especially if it was mostly text. The title and author stored in the file are kept.
Use “Everything” when the look of the page matters more than the text, for example a certificate or a marked-up drawing you don’t want reused. Very large pages are drawn at a lower resolution so your browser doesn’t run out of memory; long files work best on a computer.
Black boxes don’t hide text
A common mistake is to draw a black box over a name or number as a comment and flatten with “Forms and comments”. The box is baked into the page, but the text under it is still in the file and can be copied out. “Everything” leaves only pictures, so covered text is gone, but for private details Redact PDF is the better fit: it helps you find things like card and ID numbers, and only the pages you black out become pictures; the other pages are left as they are.
Messages you may see
- “This PDF has no form fields or comments to flatten”: there is nothing floating on the pages. If you still want to lock the whole file, choose “Everything”.
- Limits set by the owner: a PDF that blocks copying or editing is refused, because flattening would get around those limits. Remove them first with Unlock PDF and the owner’s password. A PDF that needs a password to open is refused the same way.
- Digitally signed: tick the box to go ahead. Flattening changes the file, so the signature will show as invalid. Keep the original if you may need to prove it is authentic.
- Out of memory: turning pages into pictures uses a lot of memory. Try a computer, or split a long file into parts with Split PDF first.
Everything happens in your browser: your file is never uploaded to any server. You can check: once your file is open, turn on airplane mode — the tool still works.
Questions
Will I still be able to select and copy the text?
With “Forms and comments”, yes: only the fields and comments change. With “Everything”, no: each page becomes a picture.
Can I undo flattening?
Not in the flattened file. But your original is never changed, so keep it: it still has the editable fields.
Why did my file get bigger?
You chose “Everything”: pictures of pages take more space than text. If size matters, use “Forms and comments” instead, or try Compress PDF on the result.
Does flattening make my PDF impossible to edit?
It stops anyone typing over the answers in a normal PDF reader. Someone with editing software can still change any PDF, so for a file that must stay as it is, keep your original as the reference.
How do I turn a PDF into an image instead?
“Everything” keeps a PDF whose pages are pictures. If you want separate JPG or PNG files, use PDF to JPG.
Is my file uploaded?
No. Flatten PDF runs in your browser on your own device. The file is never sent to our server or anyone else. Once your file is open you can even turn on airplane mode.
Is it free?
Yes. No sign-up, no limits on how many files, and no watermark is added to your file.
Does it work on a phone?
Yes, in any modern browser on iPhone, Android, Mac, Windows or Linux. Very large files work best on a computer, because a phone browser has less memory.