You sent a final contract. The counterparty edited a clause in their PDF editor and signed. Now the file says one thing and your records say another. Lock the document before sending and the edit window closes.
How to lock a PDF read-only
Apply an owner password via Flint's password tool and disable editing in the permissions. Compliant viewers won't allow text changes, form-field changes (unless explicitly permitted), or page additions/removals.
For signed documents, signing itself imposes integrity — any subsequent edit invalidates the signature. Lock with Flint's signing tool and the document becomes effectively read-only because edits break the seal.
Form fields and annotations
PDF permissions can be granular: allow form-fill but disallow content edits, or allow comments but disallow form-fill, etc. Choose based on the document's purpose.
For a form the recipient is supposed to fill, allow form-fill only. For a final contract, disallow all changes.
Limits
Strip-restriction tools can remove permissions for files without an open password. Print-to-PDF can produce an unprotected copy. Determined editors can re-create the document.
For most legitimate use, permissions are sufficient — they prevent the accidental and casual edits that cause version-control headaches. For adversarial editing risk, combine with digital signature.
FAQ
Does signing make a PDF read-only?
Effectively yes — any edit invalidates the signature. Most viewers refuse to save edits to signed PDFs or flag them clearly.
Can I allow form-fill but block other edits?
Yes — PDF permissions distinguish. Set in Flint when you add the owner password.
What if the recipient sends back a flat copy?
Check the document properties — if the original digital signature is no longer present, the file is a re-render. Treat as suspect and ask for the signed version.
Does locking break accessibility?
Generally no — read-only PDFs are still screen-reader accessible. Restrict edit, not read.
Read-only PDFs prevent accidental edits and most casual tampering. Lock yours in Flint before final delivery.