Firebug (other inspectors are available)

[astropos]

What tools do people use for debugging HTML and JS?

I'm a big fan of FireBug (Firefox plugin)

Also HTMLTidy is a vital tool.

Specific to Bootstrap, there's http://www.bootlint.com/
You can set up a bookmarklet so you can check for valid Bootstrap markup with one click. Recommended.

[mudmin]

I'm about to do a ton of that for Version 4. I'll let you know what I find. I have some plugins for Atom.io that are ok. I also have a bootlint plugin for Chrome.

[astropos]

Strictly notepad++ here

I've been doing a little Instagram clone on 3.0.4 and I've become a bit of a Bootstrap fan.

Thanks UserSpice and @mudmin

[mudmin]

I've been playing around with bootlint and it even finds errors on the plain google homepage. I found that ironic.