Flatten PDF

Flattening a PDF merges interactive elements — form fields, annotations and layers — into the static page, so they can no longer be edited or accidentally changed. It is the standard final step before distributing a completed form or signed document.

ColaPDF flattens by re-rendering each page in the browser. Because the output is image-based, the resulting text is no longer selectable or searchable, which is exactly what you want when locking a document for distribution.

How it works

1. Upload your PDF with form fields or annotations
2. Choose the quality setting
3. Click Flatten PDF
4. Download the flattened PDF — form fields are now permanently part of the page

Tips

• Flatten completed forms so recipients cannot alter the entered values.
• The output is image-based, so keep the original if you still need editable fields or searchable text.
• A good final step before sending a signed or finalised document.

Frequently asked questions

What does flattening do exactly?

It permanently merges form fields, annotations and interactive elements into the static page content. The result cannot be edited.

Will text still be selectable after flattening?

No. The output is image-based, so text is not selectable or searchable. Use High quality if you need it to be legible at zoom.

Why would I flatten a PDF?

To prevent recipients from modifying filled form fields, to ensure consistent rendering across all PDF viewers, or before converting to PDF/A.

Are files uploaded?

No. Flattening runs entirely in your browser.