When should I flatten?

When you are sending something as final. A filled form that is not flattened can be altered by whoever receives it, and the change is invisible — the file simply shows different values than the ones you sent.

No. The fields are gone, not disabled. Keep your unflattened copy if you might need to change the values later.

Does it make the file smaller?

Sometimes, because the form structure is discarded, but that is a side effect rather than the purpose. Use Compress PDF if size is what you are after.

Flatten PDF

Bake form fields into the page so no one can change them.

Zero-transmission processing
No watermark
Limited daily trial
Unlimited on Pro

Drop your PDFs here

or pick them from your device

Your files are never transmitted. Nothing is uploaded.

Before you start

Once the file is in, you'll see how many form fields it has and how many are filled.
Keep an unflattened copy — after flattening, the fields can't be edited again.

Secure PDF tools10 ready

Good to know

Accepts: PDF
Files at once: One at a time
Transmission: None — nothing is uploaded.

Chain it

Run Flatten PDF → Protect PDF back to back — nothing to download in between.

Set up this chain

How to do it

Add your file
Add a PDF that has form fields, annotations or a signature you want to fix in place.
Set it up the way you want
Nothing to set. Everything interactive is drawn permanently into the page: filled values stop being editable fields and become part of the document.
Download the result
Download the flattened file. It looks the same and prints the same, but nobody can change the values or delete the comments.

Questions about Flatten PDF

When should I flatten?: When you are sending something as final. A filled form that is not flattened can be altered by whoever receives it, and the change is invisible — the file simply shows different values than the ones you sent.
Can I undo it?: No. The fields are gone, not disabled. Keep your unflattened copy if you might need to change the values later.
Does it make the file smaller?: Sometimes, because the form structure is discarded, but that is a side effect rather than the purpose. Use Compress PDF if size is what you are after.