Final contract sent. You want the recipient to read and sign, not subtly change a clause and send back as if it's the original.
PDF edit protection blocks accidental and casual changes. Determined tampering requires more discipline — like signing the document properly.
Permission-based protection
Password-protect the PDF with an owner password. Set permissions to disable editing. The document opens normally but won't accept edits in standard readers.
Keep the owner password somewhere safe. If you need to edit later, you'll need it.
Combine with flattening
Flatten the PDF so form fields, annotations, and signatures are merged into the page content. Combined with permissions, this prevents most casual editing.
Flatten before password-protecting. After both, the document is as locked as a non-cryptographic protection allows.
For real integrity, sign it
Permission flags can be bypassed. Cryptographic signatures can't.
Sign the PDF with a verifiable digital signature. Any subsequent edit invalidates the signature visibly. The recipient knows immediately if anything changed.
FAQ
Can edit protection be removed?
With the owner password, yes. Without, most users can't. Specialised tools can sometimes bypass — protection is a deterrent, not a vault.
Will the recipient still be able to fill form fields?
Depends on which permissions you set. "No editing" usually still allows form filling. Set "No form filling" if you don't want that either.
Does signing replace edit protection?
Signing complements it. Edit protection prevents most changes. Signing detects any change that does happen.
What if I lose the owner password?
Edits become impossible. Keep the password somewhere recoverable.
Edit protection deters tampering. Signing detects it. Combine password protection with Flint signing for the strongest combo.