Here are the tracking events that are sent out by Impact Stack by default. You’ll see them in your Google Tag Manager (and Google Analytics), Jentis or Matomo.
actionBegin: Fired once when the supporter clicks into or tabs into the form for the first time. The event also transmits the action ID and action uuid.optin: Fired once for every opt-in/opt-out in a valid submission. All channels and opt-in status of each channel are included in the event (i.e. "email": "opt-in"). The event also transmits the action ID and action uuid.submission: Fired after a valid submission and before redirecting to the thank you page. The event also transmits the action ID and action uuid.share: Fired each time a share button (an element with data-share) is clicked. The event includes the share channel (”email”, “whatsapp”, “facebook” etc.) and the target (the url that was shared).form_start (group: "Form Interaction"): Fired once when the supporter clicks into or tabs into the form for the first time. The event also transmits the action ID.channel + _opt_in (i.e. email_opt_in, post_opt_in, group: "opt-in"): Fired once for every opt-in/opt-out in a valid submission. The event includes the value of the opt-in ("opt-in" or "opt-out").submit: Fired after a valid submission and before redirecting to the thank you page.share (group: "Share"): Fired each time a share button (an element with data-share) is clicked. The event includes the share channel (”email”, “whatsapp”, “facebook” etc.)