What does flatten mean?

Fillable fields are written into the PDF appearance so the result is more stable.

Does this flatten every annotation?

This first version focuses on form fields handled by pdf-lib.

No. Flattening runs locally in your browser.

Flatten PDF

Flatten form fields into a more stable PDF copy so filled values are harder to edit accidentally.

Enable JavaScript to use this browser-based PDF tool. The live app runs file processing locally in your browser when the tool supports local processing.

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