Flatten PDF Lock Content Permanently

Flattening merges interactive elements — form fields, annotations, highlights, and comments — permanently into the page content. The result looks identical but contains no editable or removable layers.

Yes. When form fields are flattened, their current values are burned directly into the page as static text. Anyone viewing the PDF will see exactly what was typed, but they cannot change or delete it.

Often yes — removing interactive form structures, JavaScript, and annotation metadata can reduce size noticeably. However, if the PDF already had no forms or annotations the size change will be minimal.

No. Flattening is a one-way, permanent process. Once interactive elements are merged into the page content they cannot be separated again. Always keep the original file if you might need to edit it later.

Flattening will visually preserve digital signature appearances on the page, but the cryptographic signature data will be invalidated — signature validators will no longer show the document as signed. If legal validity matters, do not flatten the PDF.

No. Everything runs entirely in your browser using the @cantoo/pdf-lib library. Your file never leaves your device — not even to our servers.