Why do people keep confusing the viewport meta tag with unzoomability? Those concepts are not one and the same. The default (i.e. most popular) viewport meta tag does not prevent zooming, while it does remove the tap delay in Firefox for Android (and also all other browsers except Safari, but version 9.1 next month will fix that).

So, if you have a responsive (mobile-optimized) site, add `<meta name="viewport" content="width=device-width,initial-scale=1,shrink-to-fit=no">` and you’re set.