What your PDFs reveal about you
A PDF carries its author, title, source app and edit dates inside the file. Where those fields live, how to see them and how to remove them.
On this page
The short version
- Every PDF can carry an author, a title, the app that made it and the dates it was created and changed.
- The same details often appear twice: once in the Info dictionary and again in an XMP packet.
- Anyone you send the file to can read them in their viewer's document properties.
- Removing them means deleting both copies, plus the app data and page previews some files keep.
When you export a PDF, the app that writes it fills in a few fields about the file. Most people never look at them. The person you send the file to can, in two clicks, and so can anyone they forward it to.
For a bookkeeper or a CPA, those fields can name the staff member who prepared the file, the client folder it came from, and the software and dates of the work. None of that is on the page, so it is easy to forget it is in the file.
Where the details live
A PDF has more in it than the page you see and print. The diagram shows the layers, top to bottom, from what a reader sees to what rides along unseen.
- The page what you see and print
- Text layer what copy and search read
- Info dictionary author, title, source app, dates
- XMP metadata the same fields again, sometimes with an edit history
- App data and thumbnails data the saving app kept for itself, and page previews
The Info dictionary is the older place. Its standard fields include Title, Author, Subject, Keywords, Creator (the app the document was written in), Producer (the library that wrote the PDF), and the creation and modification dates.
The XMP packet is a block of XML attached to the file. It usually repeats the same fields, and some apps add more, such as an edit history with a line for each save. PDF 2.0 deprecates most of the Info dictionary in favour of XMP, so newer files lean on it more, and readers are told to prefer it when both are present.
Two less known places complete the list. PieceInfo is data an app stores for its own use, such as editing state it wants back the next time it opens the file. Page thumbnails are small preview images of each page, saved inside the file by some apps.
What a reader can see
We made a test file with an author of "Sample Preparer", a title of "Client 1042 return notes" and a source app of "Sample Office Suite", and added the same author in an XMP packet. Reading the file back showed all four values. That check runs on every change to this site.
You can look at any PDF the same way:
- In Adobe Acrobat Reader, open the file and choose File, then Properties. The Description tab lists the title, author, subject, keywords, app and dates.
- In Firefox, open the PDF, open the menu at the top right of the viewer and choose Document Properties.
- In the FileMorphs PDF editor, open the file and the Document metadata panel lists every Info field and says whether XMP or app data is present.
| Field | What it can give away |
|---|---|
| Author | The name of the person or account that made the file |
| Title | Often the original file name, which can include a client name |
| Creator and Producer | The software and version your office uses |
| Created and Modified | When the work was done, down to the second |
| XMP history | A list of saves, sometimes with the apps used |
How to remove it
Clearing the fields in one place is not always enough. A tool that clears only the Info dictionary leaves the XMP packet, which still holds the author. Removal has to cover both copies, and the app data and thumbnails as well.
The PDF editor's switch, Remove metadata when exporting, does that. On Export or Compress it drops the Info dictionary, the XMP packet, PieceInfo and page thumbnails, and writes a new file. Split always makes files without metadata. The file open in the editor keeps its metadata until you export. It all runs in your browser, so the file is not uploaded.
In our test, the stripped copy no longer contained the author, the title, the source app or the XMP packet when read back.
A habit worth keeping
Check the properties of a file before it leaves the office, the same way you would read an email before sending it. If anything there names a person, a client or a folder, strip it and check again. It takes less than a minute, and the second check confirms the first.
Sources
- PDF Association, ISO 32000-2:2020 clause 14, document interchange, covering the Info dictionary, XMP metadata and page-piece dictionaries.