Flatten PDF
Lock a filled-in form so the answers become part of the page itself and can no longer be edited or accidentally changed.
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YOYOPDF provides browser-based tools for common PDF and image tasks. Fast, easy and free.
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YOYOPDF provides browser-based tools for common PDF and image tasks. Fast, easy and free.
Local by Design
Document contents stay on your device while tools process them in the browser; YOYOPDF does not upload your files.
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Our tools are optimized for speed to save your time and increase productivity.
Works Across Devices
Use YOYOPDF in a modern desktop, tablet or mobile browser. No installation required.
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All tools are completely free to use. No hidden charges, no sign up needed.
Everything You Need. All in One Place.
Use YOYOPDF for common PDF and image tasks while keeping document processing on your own device.
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View all tools →Frequently asked questions
What does flattening actually do?
It converts any fillable form fields into permanent, non-editable page content — the visible values stay, but they can no longer be typed into or changed.
Should I flatten before or after filling a form?
Flatten after filling the form (see Fill PDF Form) once you're ready to lock the answers in.
Is my file uploaded anywhere?
No, flattening happens locally using pdf-lib.