OpsGenie can send a HTTP POST request to a web accessible URL endpoint (what's often referred as webhooks) and pass alert activity data. URL endpoint can be any platform, web server, etc. as long as the URL is accessible from the Web. Webhook data includes the alert activity (create, acknowledge, etc.) as well as a subset of the alert fields (alertId, username, alias, entity, userId) as part of the HTTP request payload (JSON). Also, users can define custom headers to add the webhook call.
Integration can be created at OpsGenie Webhook Integration page.
You can add alert filter to send the activity data of particular alert types. For example: If you want to send the data to your endpoint only when an alert is created, your alert action condition will be the following;
Also you can select 'Escalate' alert action to send the data to your endpoint only when alert is escalated.
Example Webhook data for different actions can be found in this document.