How to Flatten a PDF
To flatten a PDF, merge its form fields and annotations into the page itself so they can no longer be edited. PDFDEN's free PDF flattener does it in your browser in one of two modes. Use it before you send a filled form, a signed contract or a marked-up draft.
Flatten PDF: Lock form fields into the page. Free, and your file never leaves your device.
Open Flatten PDFSteps
Open Flatten PDF and drop in the PDF.
Pick Forms to lock fillable fields into the page while keeping text selectable.
Pick Full to bake in everything, including comments and annotations. Each page becomes an image.
Run it and download the flattened PDF.
What does flatten PDF mean?
A PDF can hold layers of content on top of the page: fillable form fields, comments, sticky notes, stamps, signature images. Each one is a separate object that someone can edit, move or delete.
Flattening a PDF turns those objects into ordinary page content. A filled-in field becomes plain text printed on the page. The result looks the same, but the values can no longer be changed and the fields are gone.
It also fixes a common problem: forms that look filled in on your computer but show up empty in another app or on a printer.
Forms mode or Full mode?
Forms is the right choice for most filled forms. Field values become part of the page and the text stays selectable and searchable. The file size stays close to the original.
Full renders each page to an image, so comments, annotations and fields are all burned in, whatever kind they are. Use it when the marked-up look has to be preserved exactly. The cost is that text is no longer selectable, and the file may grow.
Flattening does not stop someone from editing the page with a PDF editor. To lock the file itself, add a password with Protect PDF.
Flatten PDF: Lock form fields into the page. Free, and your file never leaves your device.
Open Flatten PDFHow to flatten a PDF on a Mac or in a browser
Printing to PDF flattens most forms as a side effect. On a Mac, open the PDF in Preview, choose File > Print, then pick Save as PDF from the PDF menu at the bottom. In Chrome or Edge on any system, press Ctrl+P and choose "Save as PDF".
Results vary. Some viewers drop field values or comments when printing, and printing rebuilds the file, which can lose links. The flatten PDF tool gives predictable output with a choice of mode.
Flatten after you fill, sign or annotate
Flattening is usually the last step. Fill the form, add any extra notes with Add Text to PDF, place your signature with Sign PDF, then flatten so none of it moves. The guide on how to sign a PDF covers the signing part.
Work on a copy. A flattened form cannot be filled in again, so keep the blank or unflattened version in case a value needs to change later.
When not to flatten a PDF
Don't flatten a form someone else still needs to fill in. The fields disappear, and they would have to type over the page instead.
Skip Full mode for long text documents that people need to search or copy from, since every page becomes an image. Forms mode keeps the text layer.
Flattening is also not redaction. Content hidden under a comment or a shape stays in the file in Forms mode. To remove sensitive text for good, use Redact PDF and see how to redact a PDF. For everything else, the flatten tool is a quick last step before sending.