How to lock filled pdf form fields to make them read-only
- Step 1Complete all form fields — Fill in every required field before flattening — you cannot edit fields after the process.
- Step 2Upload the filled form — Drop the completed PDF into the flatten tool.
- Step 3Flatten all fields — Process the form to convert all interactive elements to static content.
- Step 4Archive or distribute — Download the flat, non-editable PDF for archiving or sending to the receiving party.
Frequently asked questions
Does flattening also remove annotations and comments?+
Only interactive form fields are flattened by default. For annotations, use the Annotation Remover tool.
Will the file size change after flattening?+
Slightly — flattened PDFs may be marginally smaller or larger depending on the complexity of the form fields.
Can I flatten a form that was signed with a digital signature?+
Flattening will embed the signature visually but removes the cryptographic digital signature. Use the Signature Viewer to verify the signature first.
Privacy first
All PDF processing runs locally in your browser using PDF-lib and pdf.js. No file is ever uploaded — only metadata counters are saved for signed-in dashboard stats.