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Flatten PDF

Local

Flatten supported PDF form fields into static content

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Flatten PDF
Local
Tool Details
Input formatsPDF
Output formatPDF
Max file size100 MB
Max files1
ProcessingLocal
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Privacy First

Your files are processed entirely in your browser. Nothing is uploaded to any server.

How do I flatten a filled-in PDF form?

Open the completed PDF and run the tool. Supported AcroForm fields are merged into the page content, so the values you typed become part of the document and can no longer be edited or cleared in a viewer. Standalone comments, highlights, and stamps are left as they are. The file is processed in your browser and downloaded locally.

About the Flatten PDF

Flatten supported AcroForm fields into the document content so their values are no longer editable. Standalone comments, highlights, stamps, and other annotations are left unchanged.

  • Lock filled-in form fields before emailing a contract so recipients cannot alter your answers.
  • Reduce form-field compatibility problems between PDF viewers and printers.
  • Create a static copy of supported AcroForm values while keeping the editable original separately.

How to use the Flatten PDF tool

  1. 1

    Upload PDF file

    Select PDF file from your device or drag file into the upload area.

  2. 2

    Review files

    Review the selected files and continue when they are ready.

  3. 3

    Flatten PDF

    Run the Flatten PDF tool to create the PDF output.

  4. 4

    Download the result

    Download the finished file. The original file stays on your device and is not uploaded.

What does flattening actually change in the file?

Interactive form fields stop being interactive. Before flattening, a filled PDF stores your answers as editable widget values sitting on top of the page; anyone who opens it can click in and change them, and some viewers will happily discard them on save. Flattening draws those values into the page content and removes the fields, so what you send is what the recipient sees. The rest of the document is untouched, and its text remains selectable.

Which annotations survive flattening here?

This tool flattens supported AcroForm fields specifically. Standalone annotations — sticky-note comments, highlights, freehand markup, and stamps that are not form fields — are deliberately left unchanged, so review markup stays reviewable rather than being burned irreversibly into the page. If your goal is to make absolutely everything permanent, including annotations, you need a rasterising step instead: run the flattened file through Compress PDF in balanced or maximum mode.

Why do filled forms look empty on someone else’s computer?

Because form values and page content are stored separately, and viewers disagree about how to handle them. A form filled in a browser’s built-in PDF viewer or a mobile preview app may save the values in a way that another program, or a printer, simply ignores — so the recipient opens a pristine blank form and assumes you sent the wrong file. Flattening before sending removes the disagreement entirely, which is why it is worth doing on any form that matters.

Are my files uploaded when flattening a PDF?

No. The documents that need flattening are filled-in forms, which by definition contain the information someone asked you for — bank details, a signature, a national insurance or social security number, medical history. Uploading that to a converter to lock the fields would be an odd way to protect it. The form is read from disk, rewritten in memory, and downloaded, with no network step involved.

How to do this offline, on the command line

Flattening means different things for annotations and for form fields; qpdf handles both.

qpdf

macOS: brew install qpdf · Debian/Ubuntu: apt install qpdf

qpdf --flatten-annotations=all contract.pdf flat.pdf

Draws annotation and form-field appearances into the page content. Add --generate-appearances first if a viewer filled fields without saving appearances.

Frequently Asked Questions

What does flattening a PDF do?
This tool converts supported AcroForm fields into static, non-editable page content. It does not flatten standalone comments, highlights, stamps, or other annotations.
Does flattening make form fields uneditable?
Yes. After flattening, the values you typed into form fields are drawn onto the page itself and the interactive fields are removed, so the answers can no longer be changed in a PDF editor.
Will my annotations and comments be preserved?
Standalone comments, highlights, stamps, and other annotations are left unchanged. Review the result in your PDF viewer before sharing it.
Is flattening the same as making a PDF read-only?
Not exactly. Flattening removes interactive elements but does not encrypt the file. To also prevent editing with a password, run the flattened file through our Protect PDF tool.

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