A filled-in PDF form is a stack of separate objects: the page, the fields on top of it, and the comments, stamps and highlights someone added. Some viewers draw them differently, and anyone can still change the fields. Flattening paints those objects onto the page, so what you see becomes part of the page itself.
This tool does that in your browser, shows you what it found beforehand and what it did afterwards, and is blunt about the side effects: digital signatures do not survive, and flattening is not encryption or protection. The PDF is not uploaded.
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Overview
About Flatten PDF
Form fields. Text fields, check boxes, radio buttons, drop-downs and list boxes are drawn onto their pages using their appearance, and the field objects are removed. Where a field has no stored appearance, one is generated; if that is impossible with the built-in font (for example for non-Latin text), the appearance already stored in the file is used instead and the report says so.
Annotations. Annotations that have an appearance stream, such as stamps, highlights, underlines, ink drawings, shapes and free text, are drawn onto the page at the position the PDF specification prescribes (the appearance box is mapped onto the annotation\'s rectangle), and the annotation is then removed. Links are navigation rather than content, so they are kept. Hidden annotations and pop-up windows are not drawn. Annotations without an appearance stream, which a viewer would have to draw itself, cannot be flattened; they are left as they are and counted in the report.
Analysis first. Before anything changes, the page lists how many fields of each type, how many annotations have or lack an appearance, how many links there are, whether the file is signed and whether it is an XFA form.
Preview. After flattening you see thumbnails of the result and can download it.
What flattening is not. The text and data are still in the file and can be copied or recovered. It is not encryption and gives no protection. Anyone can still extract the content.
Compatibility
Supported Formats
PDF files up to 80 MB and 500 pages with AcroForm fields and standard annotations. XFA (dynamic) forms are flattened from the appearance viewers show, and the XFA definition is dropped. Password-protected PDFs must be unlocked first.
Guide
How to Use Flatten PDF
- Choose a PDF and read the analysis: fields, annotations, signature and XFA notes.
- Choose whether to flatten forms, annotations or both.
- Press Flatten, check the report and the preview thumbnails.
- Download the flattened PDF and keep your editable original.
Highlights
Features
- Forms and annotations Text fields, check boxes, radio buttons, drop-downs, stamps, highlights, ink, shapes and free text.
- Analysis first Counts what is there and what cannot be flattened before you change anything.
- Links kept Navigation links are not content and stay clickable.
- Signature warning Tells you when flattening will invalidate a signature, before you do it.
- Preview and private Thumbnails of the result; nothing is uploaded.
Applications
Use Cases
- Sending a completed form so that fields cannot be edited by accident
- Making stamps, highlights and comments appear the same in every viewer and printer
- Fixing a form that prints with missing or shifted field content
- Preparing a PDF for a system that does not support annotations or forms
- Producing a final copy of a reviewed document with the review marks visible
Good to Know
Limitations
Digital signatures. Flattening rewrites the file, so every digital signature in it becomes invalid and signature fields are removed. If the signature must stay valid, do not flatten the file. The page warns you when it finds one.
Flattening is not encryption, redaction or protection: text remains in the file. It is hard to undo, so keep an editable original. Annotations without an appearance stream, hidden ones and pop-ups are not drawn. Dynamic XFA forms, JavaScript-driven appearances and unusual annotation types may not look identical afterwards; compare the result with the original.
This tool runs entirely in your browser — your file is never uploaded to our servers. See our Privacy Policy for full details.
Support
Frequently Asked Questions
Is my PDF uploaded?
No. It is read and rewritten in your browser with pdf-lib. Nothing is sent to our server.
What happens to digital signatures?
They become invalid, because the file is rewritten, and signature fields are removed. If a valid signature matters, do not flatten.
Is a flattened PDF secure?
No. Flattening is not encryption or redaction. The content is still in the file and can be copied. It only stops fields and annotations from being edited as separate objects.
Why were some comments not flattened?
Annotations without an appearance stream cannot be drawn by this tool, and hidden annotations and pop-up windows are skipped. They are counted in the report and left as they are.
Will check boxes and radio buttons look the same?
Yes, as long as they have appearances for their current state, which is how viewers draw them. The result is compared against the original in our own tests.
Can I get the form fields back?
No. Keep the editable original. A flattened PDF has no fields left.
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