# Firefox plugin to show edit and preview panels side by side

I have installed a Firefox plugin many years ago that used Greasemonkey to allow to show editor and previewer panels side by side on MathExchange (maybe other Exchanges as well).

After I reset Firefox I lost it and have been trying to search it for longer than two hours and I can't find it. I found a few posts on SE meta on the topic "preview on the right" but those posts are pretty old and are not actually pointing to a solution I was looking for.

Could someone please let me know where I can get it? Thanks.

• This Stack Apps page has a link to Stack Exchange Side-by-side Edit and Preview. It says however that it is "broken at the moment". – hardmath Mar 12 '19 at 2:47
• @hardmath Thanks! – Kay K. Mar 12 '19 at 3:20
• If you're okay with 3rd-party tool, then StackEdit might interest you. – Andrew T. Mar 12 '19 at 8:39
• @AndrewT. Thanks. Actually I have already tried it before I posted this, but the problem I had with it was that I couldn't figure out how to make \\begin{align} \\end{align} on it. I will try to figure out. – Kay K. Mar 13 '19 at 3:15
• An answer to older feature request on this meta has a link to script on Stack Apps. However, it is shown with the warning: "This script no longer works and is no longer supported. See the Stack Overflow Extras (SOX) for this functionality." You can check whether SOX might be useful for you. – Martin Sleziak Apr 7 '19 at 6:53
• StackEdit runs KaTex, which has some minor differences to Mathjax that are very annoying. For example, (1) one can only use aligned and no align (2) one cannot do equation hyperlink via \tag and \ref (3) one cannot use \require to load packages or \newcommand to define macros..... The list goes on. – Lee David Chung Lin Apr 8 '19 at 3:52
• Some convenient formatting that can be done here are in html or java, which is absent in StackEdit (and the Markdown commands there is incomplete). I tried for a while but ended up not using StackEdit except for answers longer than, say, 5000 characters with LOTS of equations. – Lee David Chung Lin Apr 8 '19 at 3:55
• StackApps post #6091 has a powerful app, and there's an answer addressing issues with Firefox. – Lee David Chung Lin Apr 17 '19 at 0:09