Hiring alerts are triggered on two cases, representing the two alert types you can set:
job_added: when a company just added a new job posting
job_removed: when a company removed an existing job posting
On the json payload, the type property allows you to identify the type of alert that has been triggered:
{"event_id": 458325,"timestamp": "2020-04-23T12:25:32.209Z","type": "job_added",// <<<< This is where you can identify the alert type"alert_name": "Hiring in marketing","event_verbose": "Acme Co. added a job: Marketing Lead","domain": "acme.co",...
Default properties
Both job_added and job_removed alert types send the same 2 event properties under the "event_properties" key: