# Do you need remote internet access to use PDF.js Express?

**URL:** <https://pdfjs.community/t/do-you-need-remote-internet-access-to-use-pdf-js-express/261>\
**Category:** FAQ\
**Created:** [September 16, 2020, 6:09pm UTC](https://pdfjs.community/t/do-you-need-remote-internet-access-to-use-pdf-js-express/261 "2020-09-16T18:09:36Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Logan](https://yyz1.discourse-cdn.com/flex031/user_avatar/pdfjs.community/logan/32/13_2.png) [@Logan](https://pdfjs.community/u/Logan)\
**Post date:** [September 16, 2020, 6:09pm UTC](https://pdfjs.community/t/do-you-need-remote-internet-access-to-use-pdf-js-express/261/1 "2020-09-16T18:09:37Z")

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Yes.

PDF.js calls home to an authentication server to verify your license key. If this request fails, PDF.JS Express will display a watermark, even if a valid key is entered.

However, our sister product, [PDFTron WebViewer](https://www.pdftron.com/webviewer/), does not call home and can work completely offline. If this is a use case you have to support, consider giving it a try!