How to flatten a PDF (lock form fields and annotations)

A PDF with fillable fields, comments or markups can look different in another viewer or print incorrectly. Flattening bakes everything into the page so nothing can be edited or move.

Steps

Open Flatten PDF. Upload the filled or annotated PDF.
Flatten. Every page is rendered to an image and the PDF is rebuilt from those images.
Download. Open the result and check that it looks exactly as intended.

Open the tool: Flatten PDF

Good to know

Form fields, annotations and any interactive layer are removed, not just disabled.
Because pages become images, the text in the result can no longer be selected or searched. Use OCR PDF afterwards if you need searchable text.
Keep the original if you may need to edit the form again.

Frequently asked questions

Can I still edit the form after flattening?

No. The fields are gone. Keep the original for edits.

Why can I not select the text any more?

Flattening turns each page into an image. Run OCR PDF to make it searchable again.

Does it make the file bigger?

It can, because pages are stored as images. Compress PDF can shrink it.

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