Questions
Can a flattened PDF be edited?
Not as a form: flattening removes the fillable fields, so nobody can retype, clear or reset the answers. But a flattened PDF is not locked like a password-protected file. Anyone with a full PDF editor can still change the page content, as with any PDF. Flattening prevents casual changes and display problems; it does not prevent deliberate tampering.
Last reviewed · 2 sources
What flattening changes
A fillable PDF keeps answers in interactive fields. Flattening draws those answers into the page and removes the fields; Readdle describes it as making “all the active elements of the file become no longer available for a change.” The result looks the same everywhere and has nothing to type into.
What flattening does not do
- It does not add a password or encryption
- It does not stop someone editing text or images with a PDF editor
- It does not prove who filled in the form or when
- It does not remove personal information from the page
When you need more than flattening
To show a document has not changed, use a digital signature. To stop people opening or editing it, use password protection or permissions, keeping in mind that permission restrictions are not strong security. To send a form without personal details, redact or replace them first.
Where PiBye fits
How PiBye handles this
PiBye’s Lock PDF flattens forms on your Mac so answers cannot be retyped and display consistently. It is not password protection, and PiBye says so on every Lock PDF page.
1.0.1 · macOS 14.8.5 or later · Apple Silicon · 1.1 GB
Frequently asked questions
Can I unflatten a PDF?
Not reliably. Flattening removes the fields; keep your original fillable file.
Does flattening remove personal information?
No. Everything visible in the form stays on the page. Redact or replace personal details separately.
Sources
- Save the file as flatten, Readdle (PDF Expert Help Center). Checked 17 September 2026.
- Flatten PDF online, Sejda. Checked 17 September 2026.