Flatten a PDF Online
Make form fields and notes in your PDF uneditable.
🔒 Your file is processed inside your browser. It is never uploaded or saved.
What is Flatten PDF?
A flattened PDF turns interactive elements, such as form fields, into ordinary page content. Answers can then no longer be edited by mistake, and the file looks the same in every viewer.
How to flatten a PDF
- Upload the PDF with form fields.
- Press Start. Fields are merged into the page.
- Download the flattened copy.
- Open it and try clicking a field to confirm it is locked.
When Flatten PDF is useful
Finished forms
Lock answers before sending.
Consistent display
Avoid viewers that render fields differently.
Printing
Make sure filled values print correctly.
Tips for better results
This tool flattens form fields. Other annotation types may behave differently. Keep an editable copy in case you need to change an answer later.
Good to know before you start
In a form, a field is an object that can be edited, while the page underneath is fixed. Flattening draws the current value of each field onto the page and then removes the field itself. The result looks identical but is no longer interactive, which prevents accidental changes and makes the document behave the same in every viewer, including mobile previews that ignore form fields. It also helps with printing, since some printers skip form fields. Flatten after you have checked all entries, because there is no going back. If the file has no fields, the output will match the input. Typical uses include sending a completed application, archiving a signed form or preparing a document for a print shop. Remember to keep a copy of the editable version in case a number or date needs to be corrected later. The tool processes one file at a time, keeps the page content sharp and does not convert pages to pictures, so text stays selectable.
Why use PDFToolkit
When you flatten a PDF with PDFToolkit, the work stays on your own device. Your contracts, ID scans and invoices are processed in the browser and are never sent to a server.
- Private: no upload, nothing saved.
- Free: no sign-up, no daily limit and no watermark.
- Fast: no waiting for files to travel over the internet.
- Everywhere: Windows, Mac, Linux, Android and iPhone.
Frequently asked questions
Can I undo flattening?
No. Keep the original if you may need to edit.
Does it flatten comments?
It targets form fields.
Does it reduce quality?
No.
Is the file uploaded?
No.