Flatten & Lock a PDF
Turn fillable form fields and page annotations into permanent, non-editable content — choose exactly what to lock in, and finalize a PDF before you share it.
Drop a PDF with form fields or annotations
How flattening a PDF works
Flatten PDF finds every fillable form field and every page annotation in a document, bakes them into the page as permanent content, and gives you back a file where nothing can be edited, extracted, or stripped out. A fillable form or an annotated PDF stays interactive by design — anyone who opens it can change the field values or edit the comments — which is exactly the opposite of what you want once a form is finalized and ready to send.
Form field flattening and annotation flattening work differently under the hood, and this tool treats them separately instead of forcing an all-or-nothing choice. Form fields flatten losslessly: their current values are drawn directly into the page as regular text, so the result stays fully text-selectable and searchable. Non-form annotations — sticky notes, highlights, comments added by other software — don't have a safe way to bake into a page without rasterizing it, so any page you choose to flatten becomes a locked image instead. The review screen shows a thumbnail of every annotated page so you can decide, page by page, whether that trade-off is worth it, and everything runs locally in your browser rather than on a server.
Common use cases
- Finalizing a filled-out application or contract before sending it
- Locking survey or intake form responses so they can't be changed after submission
- Preparing a reviewed, commented document for permanent record-keeping
- Making sure form data can't be silently stripped out and reused by whoever receives the file
- Reducing file complexity before printing, since some readers render layered forms inconsistently
Related tools
Flatten PDF — frequently asked questions
It converts fillable form fields and annotations (comments, sticky notes, highlights) into permanent, static page content — they can no longer be edited, extracted, or removed by whoever opens the file.
No — it's permanent by design once you download. Keep your original, unflattened file if you might need to edit the form or annotations again later.
Yes. If your PDF has both form fields and page annotations, you can flatten just the form fields, just specific annotated pages, or both — the tool shows you a page-by-page preview so you know exactly what you're locking in before you commit.
Form field text stays fully selectable — flattening a form is lossless. Pages with non-form annotations (comments added by other software) are rasterized into a static image to guarantee they can't be extracted, so only those specific pages lose text selection. Pages you don't select, and pages with no annotations at all, are left completely untouched.
Yes. Password Protect controls who can open the file at all. Flatten doesn't restrict opening; it locks the content itself so form data and comments can't be altered once someone already has the file.
It can. Digitally signed PDFs are cryptographically tied to their exact byte content, and flattening rewrites that content — so a signature applied before flattening will likely show as invalid afterward. Flatten first, then sign, if the file still needs a valid digital signature.
Annotate PDF already bakes its highlights and notes permanently into the page when you apply them, so there's nothing left to flatten there. This tool is mainly for PDFs with real interactive form fields, or comments added by other software like Adobe Acrobat or Preview.