Flatten PDF form fields into ordinary page content
Flatten PDF form fields so the answers are burned into the page and the fields can no longer be edited. The visible appearance is what gets drawn. An XFA form is rejected with an explicit error, not guessed. You can also remove annotations, which deletes the annotation list on each page, including comments and links.
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How to flatten PDF forms
- Add one PDF. If it is encrypted, type the password you already know.
- Confirm the file is an AcroForm you are allowed to flatten. If the catalog uses XFA, the job stops and says flattening that format is not supported.
- Leave Also remove annotations off if comments and links should stay. Turn it on to delete the annotation list on every page after the fields are flattened.
- Press Flatten PDF. Fields are burned in, then removed as fields. A file with no fields is rebuilt and the result tells you none were found.
- Download the PDF and try to edit a former field. It should be ordinary page content. The producer line is Upload Nothing (uploadnothing.com).
Flatten PDF options explained
Flatten uses the field appearances stored in the file. A field that never had an appearance may not leave visible ink. The value can still cease to be an editable field. Check the download if the form looked empty before you flattened it.
Also remove annotations deletes the Annots entry on each page. That removes comments and other annotations, and links live in that same list, so they go too. Leave the toggle off when the document still needs its links.
XFA is refused before any burn-in. The error names XFA. There is no fallback that approximates the form. Export or flatten that file in a tool that understands XFA, then come back if you still need a flat PDF this page can open.
What flat means
After a successful flatten, the form fields are gone and their appearances are part of the page content. A recipient cannot change the answer by clicking the box. That is the point of the tool. It is not encryption. Password protect PDF is how you add AES-256 afterwards, and its permission flags are advisory in some viewers.
Sign PDF does not flatten the document. It places an image. If the signature sat in a form field, flatten is what burns field appearances in. The image from Sign PDF is already flat. You do not need this page to make that image non-editable, because it was never a field.
A file with zero fields is still saved, with a warning that nothing was found, and the producer line changes. If you expected fields and the count is zero, the form may be XFA, or the appearances may live in a structure this page will not treat as fields. The XFA case is the explicit rejection.
Annotations are a separate switch
Form flatten and annotation removal are not the same action. You can burn in fields and keep comments. You can also remove annotations on a file that had no fields, in which case the warning about fields still applies and the annotation lists are deleted.
Sticky notes, highlights, and link rectangles are annotations. Turning the toggle on drops that whole list. It does not offer a choice of comment versus link. If you need the links, leave it off.
Limits, formats and output
| Accepted input | |
|---|---|
| Files per batch | 1 |
| Soft size warning | 200 MB or 1,000 pages |
| Hard stop | 500 MB total in memory |
| Output | PDF, or a ZIP when there is more than one file |
| Account | None. The tool runs in this tab. |
Your file never leaves your device
Form fields are burned in by a script running in this tab. The work runs in a Web Worker in this tab, using WebAssembly for the heavy parts, and the result comes back as a local blob. This site does not upload the file, store it, or log its name.
To verify: load the page, turn on airplane mode, and drop the file again. It still finishes. Or open DevTools, choose Network, and watch the run: there is no upload. The architecture is described on How it works.
Frequently asked questions
Why was my form rejected?
It uses XFA. Flatten PDF does not support that format and stops with that reason. It will not partially flatten the pages it understands and skip the rest. Use a file that is a normal AcroForm, or flatten the XFA elsewhere before you need this page.
Can people still edit the answers?
Not as form fields. The appearance is burned into the page and the fields are removed. Someone who can edit page content in another tool can still change pixels or vectors. Flatten is not a password. Protect PDF is the encryption step, and its flags are advisory in some viewers.
What does Also remove annotations do?
It deletes the annotation list on each page after the flatten. Comments go away. Links are annotations too, so they go away as well. Leave the toggle off if the PDF should keep its links and notes. Field appearances are burned in either way, when fields exist.
The file said no fields were found. What happened?
The document was rebuilt and the producer line was updated, and nothing was burned in because the field count was zero. If you expected a form, it may not be an AcroForm, or it may be XFA, which is rejected before this warning. The page content should otherwise match what you added.
Does flatten shrink the file?
It is not a compress pass. File size can change because the document is saved again, not because images were recompressed. Use Compress PDF afterwards if a portal cares about size. Extreme compress rasterises pages and is a different kind of flat, one that destroys selectable text.
Will a signature field become a certificate?
No. Flatten burns the appearance of the field. It does not add a cryptographic signature. Sign PDF places a flat image and is also not a certificate. If you need both the field values frozen and a drawn name, flatten and then sign, and still do not call the result a digital certificate.
Last updated 2026-09-26. By Tam.