DevTools Extensions For Web App Developers

The past year has seen many leaps made to improve developer productivity through better tooling. We're paying increasing attention to our workflow and many of us have spent time optimising our usage of tools like Grunt, Bower, Yeoman and the terminal.

Another important area worth spending time on is your debugging workflow – if you're like me, this starts with the Chrome DevTools. When building an application with a specific framework or language abstraction, there's actually some additional tooling available to you in the form of recent DevTools extensions.

In this post, I'll share a quick summary of the latest developments in this area, ranging from the recent Ember extension Yehuda Katz presented at EmberCamp through to less well known extensions for Backbone and KnockoutJS developers.

Note: Canary DevTools disables icons in the toolbar by default, but I've re-enabled them via the Settings cog to aid with visualisation.

Ember Inspector

Improve your Ember.js debugging workflow with easy inspection of controllers (just select an element rendered within a context for more information), get insights into models and their attributes, layers, bound computed properties and avoid the need to dig down into the Ember object graph to figure out what is going on.

  • Released as a preview on GitHub.
  • Install via git clone git://
  • Screencasts from Yehuda Katz
  • Additional tooling: Ember Tools

Backbone DevTools

As Backbone.js aims to provide a minimalist baseline for structuring apps, there hasn't been a huge amount of work done on it's tooling in the browser, but this extension for it is pretty neat. Inspect events, syncs, View-DOM bindings and what objects have been instantiated. A useful View hierarchy displayed in the Elements panel and you can also inspect a DOM element and the closest View will be exposed via $view in the console.

  • Released as a preview on GitHub.
  • Install via git clone git://
  • Additional tooling: Grunt-BBB

Angular Batarang

Perhaps the most mature of the extensions listed so far, the Angular team have poured a lot of time and love into Batarang. $scope can get tricky so it's helpful that it helps you inspect nested scopes, view DOM elements associated with a scope, get insights into models – selecting a scope switches to the Elements pane, analyse performance of an app's expressions and visualise dependencies

Thorax Inspector

Currently the only DevTools tooling for a Backbone extension library, this tool lets you inspect Thorax projects, Views, Models and Collections via the Elements panel. There's some special setup work required to get it recognizing Thorax projects so make sure to checkout the readme.

KnockoutJS Context

Inspect KnockoutJS context, data for any selected DOM node within the Elements panel. This is pretty useful if you're working on a complex app with many nested ViewModels.

  • Released as a stable extension on GitHub
  • Install via Chrome Web Store or git clone git://

Rails Panel

Stop tailing that Rails development.log with RailsPanel. Get insights into view rendering, DB, total request times and more. Note: in order to use this extension you need to add a set meta_request gem to your app's Gemfile. Checkout the readme for more info.

  • Released as a stable extension on GitHub
  • Install via Chrome Web Store or git clone git://

CoffeeScript Console

Whilst I don't regularly use CoffeeScript myself, I know a number of friends appreciate this extension. It exposes a console within the DevTools that live compiles CoffeeScript -> JavaScript and runs CS within the context of the current window.

Grunt DevTools

If you hate having to switch back and forth between your browser tools, the terminal and your editor you might appreciate this Grunt task runner extension for triggering Grunt tasks from the DevTools. It's really useful for quickly spinning up a LiveReload/server setup, linting, running tests or pretty much any tasks you have configured for a set Grunt project. Also works well with projects you've scaffolded using Yeoman.

  • Released as a preview on GitHub
  • Install via Chrome Web Store or git clone git://


The DevTools now make it easy to save directly back to your source files from the Sources editor. Tincr however supports bi-directional editing meaning if you save changes to a page from an external code editor, your page will be reloaded in Chrome without any manual effort on your part.

And More

There are simply too many workflow helpers to mention here, but for anyone interested, I also use:

  • JSRuntime for easily grepping JavaScript objects from the Elements panel
  • PrettyPrint for unminifying/prettifying both your JavaScript and CSS automatically when using view-source
  • LiveReload which integrates well with the official LiveReload tool (make changes to your JS/CS/Sass/markup, automatic reload. Boom)
  • CSS-Shack which lets you create sexy prototypes that export to CSS using a convenient GUI editor
  • JetBrains Chrome Extension which gives you the ability to live edit in your editor and see real-time changes in Chrome when used with WebStorm IDE

If you're not already using these, I hope you find them useful!.


  1. Nice collection there. My only issue is that the Knockout section is at the bottom, and each time I select a different DOM node to inspect, Chrome scrolls the side pane to the top, and I have to scroll it back down… annoying. Is there a way to disable this scrolling?
    Or better yet, Chrome could allow sorting these expandable sections so I can put the Knockout inspector where I want it?

    • If you’re in dock-to-right mode, each expandable panel will be treated as a tab and you should be able to get to it without having to deal with an extra scroll. That said, I think sorting of the expandable sections is a reasonable feature request. I’ll pitch it to the team and see if there’s any interest in implementing.

    • I actually saw your fork while I was writing this up :) I thought it would be best to wait until there’s been some more progress on your work there but I’m excited to see the direction you take.

  2. Awesome things Addy.
    Actually i have a problem with Devtools inspector. When i hover the mouse on page, a red border box appears around of element. How can i get rid of this?

    • A red border box might indicate that you have “Show paint rectangles” turned on. Go to the Settings cog -> Rendering and check to make sure it’s switched off there.

  3. Pingback: Tools, Tools, Tools | suepergue

  4. Pingback: JavaScript Tours and Pull Quotes | Treehouse Show Ep 35

  5. Pingback: JavaScript Tours and Pull Quotes | Treehouse Show Ep 35 | Html5 Tutorials

  6. Pingback: Wordpress, Joomla, CMS, Berlin | Revision 114: <template>, Appcache, asm.js versus Bytecode

  7. Hi, Neat post. There’s an issue along with your site in web explorer, would check this?
    IE nonetheless is the market chief and a big part of other people will miss your wonderful writing due
    to this problem.

  8. Pingback: tenalisreenivas

Leave a Reply

Required fields are marked *.