I maintain a bookmarklet that people use as an aid with the site http://nbviewer.ipython.org. The bookmarklet simply looks at the user's current URL and then opens a new tab if the current URL parses to something that will work on nbviewer. As of Firefox 21 this bookmarklet doesn't work on https:// sites such as GitHub. It works on http:// sites and everything works fine in Chrome. Text of bookmarklet is at https://github.com/jiffyclub/open-in-nbviewer/blob/master/bookmarklet/nbviewer_bookmarklet.js. Is there anything I can do to get this working for people? According to the Mozilla wiki bookmarklets should be unaffected by browser security settings: https://wiki.mozilla.org/Security/CSP/Specification#Non-Normative_Client-Side_Considerations. Here's an example where the bookmarklet will work: http://iupr1.cs.uni-kl.de/~tmb/ncso/00-introduction.ipynb And here's one where it won't: https://raw.github.com/jiffyclub/ipythonblocks/master/demos/Firework.ipynb