SantoshTec PDF

Flatten a PDF so nothing can change

Turn filled-in form fields into ordinary page content, or burn everything — fields, comments, highlights and stamps — into the page as an image. Do it before you submit, print or archive a document.

Drop the PDF you want to flatten

Handled entirely on this device.

    What to flatten
    Load a PDF to see whether it has form fields.

    Which one? Form fields only keeps the text selectable and the file small. Everything, as images also fixes comments, highlights and stamps in place, at the cost of searchable text.

    Files are processed in your browser. Check the available result or preview before downloading; some tools return text, images or metadata instead of PDF pages.

    Using Flatten PDF, step by step

    1. Drop the PDF onto the box above. The page shows how many form fields and annotations it contains.
    2. Choose Form fields only to lock filled-in answers, or Everything, as images to fix comments, stamps and highlights as well.
    3. Press Flatten PDF and check the preview.
    4. Download the flattened copy. Keep the original if you may need to edit it again.

    What "flattening" means

    A PDF can carry things that sit on top of the page rather than in it. Form fields hold your answers in separate boxes. Comments, highlights, sticky notes and stamps are annotations, stored alongside the page and drawn over it by the reader. Flattening merges these layers into the page itself, so what you see becomes part of the document rather than something laid on top of it.

    Why it matters

    Answers go missing. Form fields depend on the reader drawing them. Some phone apps, older readers and printing systems show a filled form with empty boxes, and the person receiving it sees a blank application. A flattened form looks the same everywhere.

    Answers can be changed. Anyone who receives a fillable form can edit what you typed. For an application, a declaration or an invoice, you usually want what you sent to stay as you sent it.

    Upload portals and printers. Some government and university portals reject PDFs with active form fields, and some print shops' systems drop annotations entirely. A flattened file avoids both.

    The two modes

    Form fields only asks each field to draw its current value as ordinary page content and then removes the field. Text stays sharp and selectable and the file barely changes in size. It does not touch comments or stamps, and it cannot handle answers written in scripts the standard PDF font does not cover; if that happens you will be told, and image mode will work instead.

    Everything, as images draws each page exactly as a PDF reader would show it — fields, comments, highlights, stamps and all — and saves those pictures as the new pages. Nothing can be edited, moved or deleted afterwards, and nothing hidden survives. The trade-off is that text can no longer be selected or searched, and the file is usually larger. At 200 DPI it reads comfortably on screen and on paper.

    Before you flatten

    Flattening is one-way. Check every answer first, and keep the original file somewhere you can find it: if a date turns out to be wrong, it is far easier to fix the fillable version and flatten it again than to edit a flattened page. If you have not filled the form in yet, do that with Fill PDF form, which can also flatten as it saves.

    Frequently asked questions

    Will flattening change how my document looks?

    It should not. Form fields only mode draws each answer where it already appears. In a few forms with unusual field styles the font may change slightly to the standard PDF font; check the preview before downloading.

    Can I un-flatten a PDF?

    No. Flattening merges the layers permanently. That is the point, but it means you should keep the original file if you might need to change anything.

    Why is the file larger in image mode?

    Each page becomes a picture, and pictures take more space than text. Choose 150 DPI for a smaller file, or run the result through Compress PDF if it must meet an upload limit.

    Does flattening remove the form's hidden data?

    Image mode builds a new file from pictures of the pages, so hidden data, scripts and attachments do not survive. Form fields only mode keeps everything else in the file as it was.

    Is my file uploaded?

    No. Flattening happens in your browser, on your device.

    Guides that use this tool

    Background and practical advice from the guides section.

    Related PDF tools

    Most jobs need two or three steps. These pair well with Flatten PDF.