Interactive elements like form fields, comments and stamps can look different in different viewers, and they stay editable after you send them. Flattening freezes the document as it looks now. Every page is turned into an image that includes the filled values and comments, so it prints and displays the same everywhere and can't be easily changed.
How to use Flatten PDF
- Add the PDF, with forms filled in and comments in place.
- Choose the Raster quality: 120, 150 or 200 DPI.
- Select Flatten PDF.
- Download the flattened PDF and check that everything you expected is visible.
How flattening works here
- Pages are rendered as displayed: Each page is rendered exactly as a PDF viewer would display it, including form values, annotations, stamps and drawings, and saved as an image at the resolution you choose.
- Images become the new pages: Those images become the pages of a new PDF.
- What's left behind: Because the result is built only from images, it has no form fields, no comment objects, no hidden text layers and none of the original document properties like the title and author.
Trade-offs to understand
- No selectable text: Flattening removes selectable text, so pages can no longer be searched or copied from, and screen readers can't read them. Run OCR PDF afterwards if that matters.
- File size shifts: File size often grows for text documents, which were compact as text, while image-heavy documents may change little.
- Resolution: 150 DPI suits screens and ordinary printing, and 200 DPI keeps small print sharper.
- Keep the original, editable file for your own records.
When to flatten
- Good reasons to flatten: Flatten before sending a completed form that shouldn't be edited, before printing a document whose annotations must appear, or before sharing a file whose interactive elements behave inconsistently between apps.
- A useful side effect: It also strips hidden layers and metadata as a side effect.
- Not a substitute for redaction: It isn't a substitute for redaction, because anything visible stays visible.
When people use Flatten PDF
Submitting completed forms
Send a filled application that the recipient can't accidentally edit or wipe.
Printing documents with comments
Make sure reviewer comments and stamps appear on paper exactly as they do on screen.
Sharing a final, uneditable copy
Distribute a signed or approved document as a copy whose content is fixed.
Limitations to know
Flatten PDF turns every page into an image, so text is no longer selectable or searchable and file size can grow. Resolution is limited to 200 DPI, and flattening isn't redaction: anything visible on the page stays visible in the image.
Flatten PDF: common questions
Will my filled-in form values be kept?
Yes. Values visible in the form are rendered into the page images, so they appear in the flattened file.
Can I still select text after flattening?
No. Every page becomes an image. Use OCR PDF to add a searchable text layer if you need one.
Why did my file get bigger?
Text is compact, but images of pages aren't. Choose a lower raster quality, or compress the result with Compress PDF.
Does flattening remove metadata?
The flattened file is a new document built from images, so the original title, author and other properties aren't carried over.