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Flatten PDF

Turn interactive form fields and annotation overlays into permanent static content. Everything stays on your device.

How Flatten PDF works

PDF Flatten merges all interactive form fields and annotation appearances permanently into the underlying page content. After flattening, the text typed into fields, the checkboxes ticked, the highlights added, and any other annotation layer are fixed visual elements that no reader or editor can change. The output looks identical to the annotated version, but the AcroForm layer is gone. pdf-lib performs this operation inside your browser, and the PDF remains on your device from start to finish.

Flattening is the right step before archiving a completed form, sharing a signed document, or distributing a document where you want to prevent any further annotation. Unlike printing to PDF, which re-rasterises the whole page, flatten preserves the vector content of the page and only removes the interactive layer, keeping the file compact and the text selectable. Note that flattening is irreversible: the original interactive fields cannot be recovered from the output file, so keep a copy of the original if you might need to revise the fields later.

Written by Bastien Sulyan

How to use Flatten PDF, step by step

  1. Load your filled PDF form or annotated PDF into the tool.
  2. Review the preview to confirm the visible content looks correct.
  3. Click flatten to merge all form fields and annotations into the page.
  4. Download the flattened PDF.

Common use cases

  • A completed job application form needs to be archived so the fields cannot be altered after submission.
  • A digitally signed contract is ready to send; flatten it to ensure the signature and filled fields cannot be edited by the recipient.
  • A team review PDF with highlighted sections needs to be distributed to a wider audience as a read-only marked-up version.
  • A PDF form collected from multiple respondents needs its fields frozen before being compiled into a single report.

Frequently asked questions

Can I reverse the flattening and restore the form fields?

No. Flattening is irreversible. Once the interactive layer is merged into the page content, there is no technical way to recover the original AcroForm fields from the output file. Always retain the original filled form if you anticipate needing to change any field.

How is flattening different from printing a PDF to a new PDF?

Printing to PDF re-rasterises the entire page into a bitmap, which can degrade text sharpness and increase file size. Flattening preserves the vector content and only removes the interactive annotation layer, so the output remains compact and its text stays sharp and selectable.

Does flattening remove digital signatures?

Flattening converts the visual appearance of signature fields into static page content. A cryptographic signature that was validating the document's integrity may no longer be verifiable after flattening because the page content has changed. If signature verification matters to the recipient, share the original signed PDF instead of a flattened copy.

Is my filled form sent to a server to be flattened?

No. pdf-lib runs the flattening process inside your browser tab without any network activity. Your document, including any sensitive personal data entered in form fields, never leaves your computer. You can verify this by opening your browser's network inspector before clicking flatten.

Will the text in form fields remain selectable after flattening?

Yes. Because flatten merges the field content into the PDF's vector layer rather than rasterising it, the text in form fields typically remains selectable and searchable after the operation.

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