Using ASRouter Devtools

How to enable ASRouter devtools

  • In about:config, set browser.newtabpage.activity-stream.asrouter.devtoolsEnabled to true

  • Visit about:newtab#asrouter to see the devtools.

Overview of ASRouter devtools

Devtools image

How to enable/disable a provider

To enable a provider such as snippets, Look at the list of “Message Providers” at the top of the page. Make sure the checkbox is checked next to the provider you want to enable.

To disable it, uncheck the checkbox. You should see a red label indicating the provider is now disabled.

How to see all messages from a provider

In order to see all active messages for a current provider such as snippets, use the drop down selector under the “Messages” section. Select the name of the provider you are interested in.

The messages on the page should now be filtered to include only the provider you selected.

How to test telemetry pings

To test telemetry pings, complete the the following steps:

  • In about:config, set:

    • browser.newtabpage.activity-stream.telemetry to true

    • to true

  • To view additional debug logs for messaging system or about:welcome, set:

    • messaging-system.log to debug

    • browser.aboutwelcome.log to debug

  • Open the Browser Toolbox devtools (Tools > Web Developer > Browser Toolbox) and switch to the console tab. Add a filter for for activity-stream to only display relevant pings:

Devtools telemetry ping

You should now see pings show up as you view/interact with ASR messages/templates.

Snippets debugging

How to view preview URLs

Follow these steps to view preview URLs (e.g. about:newtab?endpoint=

You can preview in the two different themes (light and dark) by adding &theme=dark or &theme=light at the end of the url.


  • Links to URLs starting with about:newtab cannot be clicked on directly. They must be copy and pasted into the address bar.

  • Previews should only be tested in Firefox 64 and later.

  • The endpoint must be HTTPS, the host must be allowed (see testing instructions below)

  • Errors are surfaced in the Console tab of the Browser Toolbox

Testing instructions

  • If your endpoint URL has a host name of, you can paste the URL into the address bar view it without any further steps.

  • If your endpoint URL starts with some other host name, it must be allowed. Open the Browser Toolbox devtools (Tools > Developer > Browser Toolbox) and paste the following code (where is the hostname of your endpoint URL):

  • Restart the browser

  • You should now be able to paste the URL into the address bar and view it.