Flatten PDF forms and comments
To flatten a PDF means filled-in form fields, comments, stamps and highlights become a fixed part of the page. The document then looks the same everywhere, prints correctly and cannot be changed by accident. Everything happens in your browser, with no upload.
Source: Adobe – ISO 32000-1:2008 Document management – Portable document format (PDF 1.7). Updated: .
How it is calculated
A filled-in PDF form does not look the same everywhere: some apps hide the entries, fields shift on phones, and any recipient can change the values. Comments and stamps go missing when printing or in simple preview apps. Flattening fixes this by saving everything as fixed page content – something many agencies, banks and print shops ask for.
How it works
- Drop in the PDF. The tool shows how many form fields, comments and links it contains.
- Choose a mode: forms and comments (recommended), form fields only or everything as an image.
- Click “Flatten PDF” and download the new file.
What happens technically
Every form field and comment carries its own appearance (ISO 32000-1, 12.5.5 “Appearance Streams”). Flattening draws exactly that appearance into the page content at its place and removes the interactive element. That is why text stays real text – selectable, searchable and sharp in print. Links are kept, hidden comments are dropped. In “Everything as an image” mode, each page is rendered with pdf.js at the chosen resolution and rebuilt as a JPEG; afterwards nothing can be edited, but text can no longer be copied either.
Honest limits
- Flattening is not redaction: text underneath a flattened comment or box remains in the file. To really black out content, use the redaction feature of Edit PDF.
- Fields without a stored appearance are rebuilt; unusual fonts may be replaced by Helvetica.
- Digital signatures become invalid. Password-protected PDFs cannot be edited.
Still need to fill in the form? Use Edit PDF; to sign it, Sign PDF.
Frequently asked questions
What does it mean to flatten a PDF?
Flattening turns form fields, comments and stamps into a fixed part of the page. The document then looks the same everywhere and cannot be changed by accident.
How do I flatten a filled-in PDF form?
Drop the PDF in here, choose “Forms and comments” and click “Flatten PDF”. Your entries stay visible, but the fields can no longer be edited.
Why can others not see my filled-in form fields?
Some programs and phone apps do not show form values or recalculate them. After flattening, the entries are normal page content and visible everywhere.
Is the text still searchable after flattening?
Yes, in “Forms and comments” and “Form fields only” mode. Only “Everything as an image” turns each page into a picture.
Can flattening be undone?
Not reliably. Keep the original if you might want to change the form later.
Is my PDF uploaded?
No. Flattening happens entirely in your browser.
Sources and legal basis
- Adobe – ISO 32000-1:2008 Document management – Portable document format (PDF 1.7)
- pdf-lib – Andrew Dillon (MIT)
- ISO 32000-1:2008 – 12.5 Annotations, 12.5.5 Appearance Streams (Algorithm), 12.7 Interactive Forms
- pdf.js – rendering with annotations (Mozilla, Apache-2.0)
- pdf.js 6.3.289 licence (Apache-2.0)
- Open-source licenses of the libraries used (MIT, LGPL-3.0)
As of:
Related tools
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