Flatten PDF

What flattening a PDF means

A fillable PDF contains interactive form fields: text boxes, checkboxes, drop-downs and radio buttons that sit on top of the page. Annotations such as comments, highlights and stamps behave similarly, as separate objects layered over the content. Flattening a PDF merges those layers into the page itself, so what you see is permanently what you get. The values cannot be changed by accident, every viewer shows the same result and printing behaves predictably.

Two ways to flatten

The Form fields only mode uses pdf-lib to regenerate each field's appearance and draw it into the page content, then removes the interactive form. Everything else is untouched, so text stays selectable and file size barely changes. The tool tells you exactly how many fields were flattened. Use this mode for filled applications, contracts and tax forms you want to lock.

The Everything (print-flatten) mode first flattens the form fields, then renders every page with pdf.js at the DPI you choose and rebuilds the document from page images. Because the output is pictures, annotations, stamps, highlights and signature overlays are all baked in, which is what a print-to-PDF flatten does. The trade-off is that text is no longer selectable or searchable, and the file can grow at higher DPI. 150 DPI is a good balance for reading; 300 DPI suits printing.

Privacy and good practice

Forms often hold names, addresses and identity numbers, so uploading them to a random website is risky. This flattener runs entirely in your browser: the PDF is read from memory, processed locally and offered as a download. Keep your original fillable file in case you need to edit the answers later, because flattening cannot be undone. After flattening, open the result and check that every value appears where you expect. If an annotation or field is still missing, try the Everything mode, which captures the page exactly as a viewer draws it. Password-protected PDFs need to be unlocked first.