Hidden content
See what a document carries that nobody would see on its pages — scripts, attachments, metadata, hidden layers, earlier versions — and take it out.
A PDF can carry a lot that isn’t on its pages: scripts, instructions to open other files, whole attached files, the author’s name and computer, content on layers that are switched off, and every earlier version of itself. Before you send a document outside your organisation, check what it’s carrying.
Nixt PDF shows you the report first and takes nothing out until you choose, so you can see what it found and keep what you meant to send.
Checking a document
- On the Protect tab, click Hidden content… (or choose More › What this document is carrying…).
- Read the What this document is carrying dialog.
When there is nothing to find, the dialog says Nothing hidden. No scripts, no attachments, no metadata, no earlier versions — this document is what it appears to be.
Otherwise it says Everything below is in the file and none of it is on the page. Taking it out rewrites the document, so the undo history goes with it. and lists each kind of thing it found, with how many:
| Finding | What it is | Ticked to start with |
|---|---|---|
| Scripts | JavaScript the document asks a reader to run — on opening it, on turning a page, or on filling in a field. | Yes |
| Actions that reach outside the document | Instructions to launch a program, open another file, or send the form somewhere. | Yes |
| Files carried inside | Whole files travelling in the document, which most readers never show. | Yes |
| Metadata | The author, the application, the dates, and the XMP record — which often names a person, a computer and a folder nobody meant to send. | Yes |
| Hidden layers | Content on a layer that is switched off. It is in the file and one click shows it. | Yes |
| Hidden marks | Comments and stamps flagged not to be drawn. Not drawn is not gone. | Yes |
| Comments and markup | Notes, highlights and drawings left on the document. | No |
| What the form was filled in with | The answers typed into the fields. | No |
| Earlier versions | Every previous save is still in the file, in full, and can be read by anybody who looks. | Yes |
| Objects nothing points at | Content left behind by an earlier edit. Unreachable is not deleted. | Yes |
Some findings add a detail in brackets, such as which fields carry answers.
Comments and form answers start unticked, because they are often what you meant to send.
Taking it out
- Tick each kind of thing to take out, and untick what to keep. Clicking the finding’s name ticks or unticks it too.
- Click Take it out. It’s dimmed when nothing is ticked.
The message says Taken out and the file rewritten. Save the document to write it to disk.
What happens:
- The document is rewritten as a single version, with only what’s left.
- Hidden layers have their content taken off the pages. The layer’s switch isn’t deleted on its own, because that would make the hidden content visible.
- The undo history is cleared, so this can’t be undone.
- A password-protected document keeps its password.
- Digital signatures in the document stop matching.
If nothing of a chosen kind could be found when it came to it, the message says There was nothing of that kind to take out.
Related pages
- Redaction — removing text from the pages themselves.
- Document information — properties, metadata, layers and attached files, one at a time.
- Reducing file size — which also drops earlier versions.
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