Flatten a PDF: Forms Only or the Whole Page?

A filled form that renders differently in two viewers is not finished. Flattening fixes the appearance, but the mode decides whether the file stays a searchable document or becomes a set of page images.

Why this comes up

Forms are filled in one application and opened in another, and the widget appearance is not guaranteed to survive the trip. Archiving, printing and signing all depend on the page looking the same everywhere.

Check before you run it

• Use only form fields when the text must stay searchable. This mode bakes the widgets into the page and leaves annotations and the text layer alone. The file stops being fillable but remains selectable, searchable and small.
• Use all content only when the page itself must be frozen. Every page is rendered at the resolution you choose, so fields, annotations and text all become part of one image. The result is predictable, but no longer searchable and usually larger.
• Pick a resolution for the destination. 150 DPI is readable on screen and in ordinary office printing; 300 DPI is the safer choice for archival or fine print. The resolution only matters in all-content mode.

When to reach for it

• A completed form is going into an archive. Freeze the fields so the answers cannot be changed, while keeping the text searchable for whoever indexes it later.
• A design-heavy page must print identically everywhere. Rasterise the page when fonts, transparency or overlays render differently across viewers and printers.

One question we get

What does flattening do to form fields?

It bakes fields and overlays into the pages — values stay visible as plain text but nothing is fillable anymore. Ideal before printing or archiving a signed document.

Where it fits

The tools people usually open next to Flatten:

• Repair — Recover data from a corrupted or damaged PDF document
• Compress — Reduce the size of your PDF.
• Grayscale — Make a PDF text and images grayscale

Every tool works on a copy, so the original file is never touched. Uploads are stored under an unguessable id and deleted automatically two hours after you last open them; nothing is listed, shared or indexed. More on the security page.