Lock filled-in form fields so they can no longer be changed.
When is it useful? Flatten PDF locks a filled-in form so its fields can no longer be edited — important before you email a completed application, contract or tax form.
Good to know: all form fields — text boxes, checkboxes and dropdowns — become a fixed part of the page, so the values you see stay exactly as they are and can no longer be edited. If the PDF has no form fields, the tool tells you and nothing is changed.
| Form part | After flattening |
|---|---|
| Text boxes | Fixed part of the page |
| Checkboxes | Fixed part of the page |
| Dropdowns | Fixed part of the page |
| Values you see | Stay exactly the same |
| Editing | No longer possible |
Browser processing: your files are processed on your own device and are never uploaded to our server.
A fillable PDF form keeps its answers in interactive fields, which anyone can change later — and some viewers display filled fields differently or not at all. Flattening turns the fields and their current values into normal page content, like ink on paper.
All form fields in the PDF — text boxes, checkboxes, radio buttons and dropdowns — are converted into fixed content showing exactly the values they contain now. The fields disappear and cannot be edited any more. The rest of the document is unchanged. The result note tells you how many fields were flattened.
Flatten the final version of a completed application, contract or tax form before emailing or uploading it, so the receiver sees your answers exactly as you entered them in every viewer. Do not flatten blank forms you want others to fill.
“Has no form fields to flatten”: the PDF is already flat. A field looks empty after flattening: it was empty before — fill it with Fill PDF Forms first. You need to change an answer: go back to your unflattened copy.
Keep an editable copy, flatten only finished documents, and open the flattened file once to check every answer.