Flatten PDF
Flatten PDF form fields and annotations so nobody can edit them.
How do you flatten a PDF so the form can't be edited?
Flattening a PDF turns everything that was editable — the fields of a filled-in form and, if you choose, comments and highlights — into a fixed part of the page. Docuboxer does it in your browser: load the PDF, pick a mode and download the result in seconds. In Forms mode, each field's value is drawn onto the page and the field itself disappears; text stays selectable and the file size barely changes. In Everything mode, every page becomes an image with forms and annotations baked in, at 150 or 300 DPI. It is free, needs no signup, and your file never leaves your device — which matters when the form carries names, addresses or signatures. Whatever you send can no longer be altered by accident, and it looks the same in every PDF viewer.
How to use Flatten PDF
- Drop your PDF into the upload zone or pick it from your device. The tool immediately tells you how many form fields and annotations it contains.
- Choose a mode. Forms flattens only the fields and keeps your text selectable. Everything (rasterize) also locks comments, highlights and stamps, but turns every page into an image. In that mode pick 150 DPI for screens or 300 DPI for printing.
- Click Flatten PDF. In Everything mode you will see progress page by page, because drawing each one at high resolution takes a few seconds.
- Download the flattened PDF and open it to check that your values are still visible. If a field with emoji, Cyrillic or other special characters could not be drawn in Forms mode, the tool warns you and suggests running it again with Everything. Your original file is never modified.
Common use cases
Send a filled-in form that can't be changed
You completed an application, a lease or a school form and want to be sure nobody edits your answers after you send it. Once flattened, the fields stop being editable and your entries are fixed on the page.
Make the form look the same in every viewer
Some phone, email and browser viewers draw filled fields badly, showing empty boxes or clipped text. A flattened PDF shows the same thing in Acrobat, in Preview and on your phone.
Archive a finished paperwork file
When a form is final, it should be stored as a document, not as a template. Flattening it stops someone from overwriting a value months later without noticing.
Lock in review comments and highlights
If you marked up a document with notes, highlights or stamps and want them to arrive as part of the page, Everything mode burns them into each page image, so recipients see them even if their viewer ignores annotations.
Get a PDF ready for printing or an upload portal
Government portals and some print shops reject PDFs with interactive fields, or print them without the values. Flattening before you upload avoids rejections and blank printouts.
Frequently asked questions
What does it mean to flatten a PDF?
It means converting editable content into a permanent part of the page. For a form, the value you typed into each field stays drawn on the document while the field itself — the box, the cursor, the dropdown — is removed. You can no longer refill or change it as a form.
Does flattening make a PDF impossible to edit?
Not completely. It stops the file from being edited as a form, but anyone with a PDF editor can still change the underlying content. Rasterizing with Everything mode makes tampering much harder, since each page becomes an image. To control who can open or print the file, add a password with /protect.
Why aren't comments and highlights flattened in Forms mode?
Forms mode relies on the form-flattening routine of pdf-lib, which only handles form fields. Comments, highlights, stamps and links are different kinds of annotation and are left as they are. To lock them in, use Everything (rasterize) mode, which draws them into each page image.
Do I lose selectable text when I flatten?
Only in Everything (rasterize) mode, where each page becomes an image and you can no longer search or copy its text. In Forms mode the text stays real text and the file size barely changes.
Is my file uploaded to a server?
No. The PDF is processed in your browser on your own device and never travels over the internet, which matters when a form contains personal, tax or medical data. It is also free, with no signup and no hourly task limits.
Can I flatten a password-protected PDF?
First remove the protection: the tool refuses encrypted files so it doesn't leave them corrupted. Use /unlock with the password you know, flatten the result and, if you like, protect it again with /protect. To also clear hidden data from the file, see /pdf-metadata and /sanitize.