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Flatten PDF online, free – Lock forms and signatures

Permanently lock form values, digital signatures, and comments for secure sharing.

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Flatten PDF bakes interactive AcroForm fields, radio buttons, dropdowns, annotations, and digital signatures directly into the static vector content of each page.

Flattening prevents form tampering, ensures cross-platform compatibility across all mobile and desktop PDF readers, and prevents signature loss when printing or emailing legal documents.

How to use Flatten PDF

  1. 1Select or drop your interactive PDF form or signed document.
  2. 2Review document details and page count.
  3. 3Click Flatten PDF.
  4. 4Download your secured, static flattened PDF instantly.

Frequently asked questions

What does flattening a PDF mean?
Flattening converts interactive elements (fillable form fields, checkboxes, signatures, and annotations) into permanent, non-editable graphics on the page layer.
Why should I flatten my PDF?
It ensures that values cannot be edited or erased, and prevents form entries from disappearing when opened in third-party viewers or sent to printers.
Are my completed forms uploaded to a server?
No. The flattening process runs 100% locally in your browser memory using WebAssembly. Confidential financial and legal form data never leaves your device.

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