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Marionette Inspector


The inspector makes it possible to understand how your App works, without needing to understand how all the code works. This is possible because everything's one click away. You'll be amazed at how quickly this changes everything.

  • Visualize the view hierarchy with the UI tree
  • Visualize application activity with a full history of actions
  • Inspect view ui, events, listeners, properties
  • Inspect model attributes, listeners, properties
  • Explore Radio channel events, requests, commands
  • Explore application with an inspector magnifying glass
  • Jump between the inspector elements and source panel with intelligent links

Try it out on a live app!

Once you've installed the Chrome or Firefox extension, open the DevTools, click on the "Marionette" tab, and inspect this app!

Marionette Wires

Getting Started

Download it

The inspector should work out of the box with most setups. You can download it from the Chrome Web Store.


  • Load the app in Google Chrome or Firefox
  • Open the devtools (F12 or Ctrl + Shift + I)
  • Select Marionette tab
  • Click in 'Start the Inspector!' button

The extension icon next to URL bar has no functionality and can be ignored



If you're either using Browserify or Webpack or not exposing Backbone & Marionette as globals, you'll need to add one block to your setup.

if (window.__agent) {
  window.__agent.start(Backbone, Marionette);

Note this line should be placed after all underscore, backbone, and marionette CommonJS require calls, but before Application or View classes are defined.

Since EcmaScript import statements are hoisted, i.e., always called in the start of the module, putting __agent.start call before the import of a module that defines an Marionette class will not work. See related issue. When using EcmaScript modules is recommended to put the __agent.start call in a separated module as in Marionette Wires

UI Layout

The topmost view must be set to layout or rootView property of a Marionette Application instance. Alternatively, the view instance show in Aplication.region will be used to build the UI tree.

Examples here and here

Frequently Asked Questions

If you have any additional questions, check out our FAQ.

Usage Analytics

The Inspector gathers usage analytics to better report on inspector statistics such as average weekly users and popular features as well as to report on marionette patterns such as library versions in usage and architectural / api patterns. If you would prefer to disable analytics it is easy to do so:

if (window.__agent) {
  window.__agent.disableAnalytics = true;

Current version does not implement usage analytics

Play with it locally

Follows these these steps in the Install Guide and you should be up and running in no time. Read the agent overview to understand how the inspector gathers all the information.

TLDR version

1. Download the Extension

git clone

2. Build the Extension

npm i
npm run bower
grunt build

3a. Install in Chrome

1. go to the Extensions tab in chrome > Window
2. check the "Developer Mode" checkbox
3. click the "Load unpacked extension" and select the extension folder in the repo

3b. Install in Firefox

1. go to the Add-ons page (`about:addons`)
2. click on preferences button (in top right) and select "Debug Add-ons"
3. click the "Load Temporary Add-on" and select the extension folder in the repo

Open Source (a.k.a. you)

The inspector is built with 100% open source love. That means, we absolutely want your help and your passion. If you want to get involved, stop by and say hello here. We've got tons of help wanted tickets and would be be happy to setup a 30 minute screenhero pairing session to help you get started. Many of our contributions, even some of the best ones like the Activity pane, came from first time contributors.

Special Thanks

Etsy - The Inspector was largely built as an open-source project at Etsy.

Backbone-Debugger - The Inspector is built on top of the Backbone Debugger core, written in large part by @Maluen.