Ask HN: Can I track browser extensions users are using while browsing my site?
Do you mean plugins such as Flash and Java? These can be enumerated with Javascript code in Gecko/WebKit browsers[1]. AFAIK there's also something similar for IE.
When it comes to extensions such as HTTPS Everywhere and AdBlock etc I don't think it's supposed to be possible. Some extensions may unintentionally leak information that can be used to detect them though[2]. What are you trying to do?
[1] https://developer.mozilla.org/en-US/docs/Web/API/NavigatorPl... [2] http://ha.ckers.org/blog/20060823/detecting-firefox-extentio...
No, not plugins, extensions. I'm trying to find out two things: 1. Trying to find out what extensions are used most of the times on my service so I can create a better experience by implementing those features. (Like if I would be Tumblr I would like to track how many users are using http://missing-e.com/ or similar extensions.) 2. Trying to find out how much revenue do I loose because of ad blocking extensions.