How to prevent Pdf's connecting

I am aware some PDF’s transmit information (IP address etc.) via the internet when they are opened. I have got into the habit of using Foxit to prevent this.

  1. Does DevonThink allow information transmission when a PDF is opened?
  2. If so can it be prevented?

What PDFs?
Do you actually have one that exhibits this behavior?

I can imagine how it’s possible that something inside a PDF could be coerced to transmit out into the internet, but I’m unaware of any PDF reader that proactively prevents that. I looked at the Foxit web site and can’t find any reference to that as a feature.

Could you please give me, for my own education, the Foxit URL for their description of what they do?

See the safe mode settings in the data sheet.

Adobe does have similar settings but they are hidden and apparently not that strict.

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This a screenshot from Foxit Phantom (the paid version which I use)

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There are a few companies that add tracking to PDF’s. Publishers regularly track PDFs for example academic research papers, legal documents, etc and there are a number of companies that perform this service for example:

Its pretty common practice in publishing particularly with protected / copyright material. However others can track them too.


ANd there are loads of “self-help” ways of tracking PDF’s -

Do you have more details on this? Acrobat overtly offers a tracking function (e.g. so one could see who has signed a document, who still needs to be reminded to do so, etc.), but I can’t find any obvious way to deactivate what I understand you to be describing, which would be more along the lines of a generic tracking pixel or similar.

Actually I doubt that the PDFkit of macOS supports these advanced (or actually rather obscure) features of the PDF format.

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With Little Snitch one could prevent such activities.



Using Little Snitch to block these connections is of course possible, but since Devon has web browser capabilities I allowed ports 80 and 443, which means these connection blocks have to be set up proactively as global rules.

Searching my blocklist subscriptions (from revealed that these trackers aren’t part of them.

On iOS, I use AdGuard with DNS based filters from Energized. Looking through Energized’s flagship unified list with 1,3 million domain blocks also reveals that these trackers aren’t included. Neither does include them.

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