Flatten PDF Online – Lock Form Fields and Annotations into the Page
PDFmuto flattens form fields, annotations, and comments into the page itself, right in your browser — the file looks identical, but nothing can be edited anymore and no data is uploaded.
- No file limits
- No registration
- Free forever
- PDFs never leave your browser
Drop your PDF here
Supported format: PDF
Flattening merges form fields, annotations, and comments into the page itself — the file looks identical, but fields can no longer be edited and values are locked in.
How to Flatten a PDF Form
Upload PDF
Drop the PDF with form fields or annotations you want to lock.
Flatten the Fields
Click the button to merge every field, annotation, and comment into the page.
Download Flattened PDF
Download the locked document and share or archive it with confidence.
The Final Step Before You Share a Completed Form
Filled forms travel better when they are flattened. The values become part of the page, so recipients see exactly what you filled in and nothing can be changed by accident — or on purpose.
Flattening also removes the inconsistencies that appear when different PDF viewers render interactive fields differently, giving you one stable version for print, archive, and e-signature workflows.
Flattening Details
| Fields flattened | Form fields, checkboxes, radio buttons |
|---|---|
| Also flattened | Annotations, comments, signatures |
| Text stays selectable | Yes |
| Editable after flattening | No — that is the point |
| Registration | Not required |
| Upload | None, processed on your device |
Your PDFs never leave your browser
All processing happens locally on your device. Nothing is uploaded to a server, stored, or tracked.
Frequently asked questions
What does flattening a PDF do?
It merges interactive form fields, annotations, and comments into the page itself. Visually nothing changes, but the fields stop being editable.
Why flatten a PDF before sending it?
Flattening is the standard way to lock a completed form before sharing or archiving it, so nobody can silently edit the values you submitted.
Will flattening change how my document looks?
No. Flattening keeps the exact appearance — text, layout, and filled values stay as they are. Only the editability changes.
Is flattening the same as converting to an image?
No. A flattened PDF keeps selectable text, bookmarks, and structure — it is still a real PDF, just with locked content.
Learn more about PDFs
Read practical guides for working with PDFs without uploading your files. Browse all guides →