It works. no automatic downloads anymore and no "file:///C:/Users/<User>/Downloads/thepdf.pdf" in the URL bar, but the actual URL.

Does the job, thanks – tested with the PDF reports under https://ec.europa.eu/digital-single-market/en/news/annual-self-assessment-reports-signatories-code-practice-disinformation-2019#block-views-39e10d54fad34071dca96fe7d7133f38

Four stars here.

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Five stars to Display inline https://addons.mozilla.org/addon/display-inline/ for having a longer history and offering a support address.

This add-on seems very usefull for me. I'm working with a few web applications where I have to download and print pdf documents from. Only one of these apllications send pdf with application/pdf content, two of them use octet-stream. That's why I was always forced with dialog to choose if I want save or use viewer and there was no reason to omit this dialog (this is well known issue - I use Firefox 60.0 currently). With this add-on I could achieve common solution for all these three web applications - in my solution a viewer is choosen. One side effect is visible that if we have pdf attachments in e-mails they are also open with a viewer now because I have viewer set in firefox's Applications settings for pdf documents. But I'm going to improve this solution with bash script.

Does not work for me at all.