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Flatten PDF
Flatten any PDF into an image-only document. Lock filled forms, bake in annotations, ensure consistent rendering. Free and private. 100% free, private,.
How to use
Upload PDF — Choose a PDF with form fields, annotations, or layered content to lock down.
Choose Quality — 150 DPI / 85% works for most documents. Use 200 DPI for archival quality.
Download Flattened PDF — Get an image-only PDF — uneditable, consistent across viewers, ready to share or archive.
The PDF Flatten tool re-renders every page of a PDF into a single image and rebuilds the document as an image-only PDF. This locks in form field values, annotations, signatures, and watermarks — producing a file that looks identical in every PDF reader and cannot be edited.
Why flatten a PDF?
Lock filled-in forms — applicants cannot un-fill or alter your form responses.
Bake in annotations — comments and highlights become permanent.
Consistent rendering — fixes "looks different in Chrome vs Adobe" issues.
Prevent text copying — useful for IP-sensitive deliverables.
Hide layered content — flatten optional content groups (OCGs).
How it works
Each page is rendered by pdf.js to a canvas at your chosen DPI, encoded as a JPG, and embedded into a new PDF via pdf-lib. Form fields are rendered with their current values, so flattening freezes the visible state.
Limits
Flattening uses considerable memory. The tool caps at 100 pages per run; split larger PDFs first using our Split by Range tool.
Privacy
All rendering and re-encoding happens inside your browser. Sensitive filled-in forms (tax, HR, medical) never reach a server.
Frequently asked questions
What does 'flattening' a PDF mean?
Flattening converts every page into a single rasterised image, baking in form field values, annotations, comments, and any layered content. The result looks identical in every PDF viewer and can no longer be edited or have its text selected.
When should I flatten a PDF?
Flatten when you need to (a) lock filled-in form data so it cannot be changed, (b) hide annotations from being toggled off, (c) ensure consistent rendering across viewers (Adobe vs Chrome vs Preview), or (d) prevent text copying for IP-sensitive documents.
Will the file size change?
Usually larger for text-heavy PDFs because text becomes image pixels. For PDFs already heavy with images, the change is small. Use 100 DPI for smaller files, 200 DPI for archival.
Why is text no longer selectable?
After flattening, each page is one image. Text is no longer 'text' — it's pixels. This is the intended behaviour. Keep your original PDF if you need editable text later.
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