How to flatten a filled PDF form
Updated
Contents
To flatten a PDF form, open Flatten PDF, pick the filled PDF and select Flatten form fields. Each field's current value is drawn into the page and the field itself is removed, so the answers can no longer be changed in a PDF viewer. It runs in your browser, so the file stays on your device.
Flattening is the last step of a form's life. Fill it in first — Fill Forms completes a PDF's existing form fields in your browser — then flatten the copy you are about to send.
Step by step
- 1Open the Flatten PDF tool and pick your filled PDF — it stays on your device.
- 2Check that the answers are final — the flattened copy has no fields left to change.
- 3Select Flatten form fields.
- 4Read the result: it says how many form fields were flattened, or that none were found.
- 5Download the flattened PDF, and keep the original if you may need to edit the answers again.
What gets flattened
Every fillable form field — text boxes, checkboxes, radio buttons, dropdowns and list boxes — is drawn into the page with its current value and removed as a field. Comments and layers are not form fields, and they are re-saved unchanged.
A PDF with no form fields is re-saved as it is, and the result says no fillable form fields were found — so a file that only looks like a form, such as a scanned paper form, is not changed.
When flattening is refused
A text field holding characters outside the basic PDF alphabet — Bengali, Chinese or Greek, for example — cannot be flattened yet, because the field is drawn with the form's own font. Instead of producing a page with those characters missing, the tool stops and says which characters it could not draw.
After flattening
Flattening stops the answers being edited, but anyone who has the file can still open and read it. If it should only open for certain people, Protect PDF adds a password with AES encryption. That step runs on a secure server rather than in your browser.
Common questions
Why flatten a filled PDF form?
So the answers you send are the answers that are read. A flattened copy has no fields left for anyone to change, and its values are part of the page rather than something a viewer draws on top of it.
Can I undo flattening?
Not in the flattened copy — its fields are gone. The file you picked is not changed, so keep it if you may need to edit the answers again.
What if my PDF has no form fields?
Nothing is flattened: the file is re-saved as it is, and the result says no fillable form fields were found.
Does my PDF leave my device?
No. Flatten PDF runs entirely in your browser, and the file stays on your device from start to finish.
How large can my PDF be?
Up to 100 MB per file.