Keeping the form editable preserves interactive controls
When Flatten Form is turned off, 1into1 saves the filled PDF while retaining the AcroForm structure. Supported fields remain normal form controls that a compatible PDF reader can continue to edit.
Choose this when the recipient still needs to revise answers, complete additional fields or reuse the form.
Flattening removes normal form-field interactivity
When flattening is enabled, the filled field appearance is applied to the page and the interactive form widgets are removed from the finished copy.
Adobe describes flattening similarly: the graphical appearance remains, but the form field is no longer interactive.
1into1 also cleans stale form-widget references
After flattening, the tool removes remaining Widget annotation references that can be left behind by some form structures, while preserving unrelated normal annotations when possible.
It then copies the flattened pages into a fresh PDF document so stale AcroForm objects from the source are not intentionally carried into the static finished copy.
Flattening is not the same as document security
A flattened field is no longer a normal interactive form control, but flattening should not be treated as encryption, access control or a promise that no PDF editor can alter the page.
Use password protection and appropriate sharing controls when you need access restrictions rather than only a static form appearance.
Keep an editable original before flattening
Flattening is best treated as a finalization step. Keep the original interactive form separately if you may need to change the answers later.
Adobe likewise recommends retaining the original because interactive elements cannot simply be restored from a flattened final copy.
Official sources reviewed
- Adobe Acrobat — How to flatten a PDFAdobe explains flattening as integrating interactive elements into static document content and recommends saving an original copy first.
- Adobe AEM Forms — Flattening formsAdobe documentation defines flattened form fields as retaining graphical appearance while no longer remaining interactive.