The Axon Pixel Helper is a Google Chrome extension that helps you debug and validate your Pixel installation. It allows you to see the events your site produces and to check that they are present.
You can find and install the Axon Pixel Helper here.
Axon recommends that you pin the extension to your search bar. After you install it, you can navigate around your site (including by clicking to a new page) and the extension will track all events sent to Axon.
The plugin will indicate each event with a status:

You can click an event to see which specific fields are missing.
Axon recommends that you review a sample flow that captures the events you configured your website to trigger. Verify that each event is sent correctly by using the Pixel Helper extension.
view_item event.add_to_cart event.begin_checkout event.purchase event.Also, the page_view event should fire when you visit any page during the flow.
generate_lead event.Also, the page_view event should fire when you visit any page during the flow.