Free-format Webhook is mostly used for custom integrations via scrips. Use any http client, e.g. curl to send POST requests with any payload.

Request example:

curl -X POST \
  {{ alert_receive_channel.integration_url }} \
  -H 'Content-Type: Application/json' \
  -d '{
    "alert_uid": "08d6891a-835c-e661-39fa-96b6a9e26552",
    "title": "The whole system is down",
    "image_url": "https://upload.wikimedia.org/wikipedia/commons/e/ee/Grumpy_Cat_by_Gage_Skidmore.jpg",
    "state": "alerting",
    "link_to_upstream_details": "https://en.wikipedia.org/wiki/Downtime",
    "message": "Smth happened. Oh no!"
}'

Next steps:

1. 1. Add the routes and escalations in Escalations settings
2. 2. Check grouping, auto-resolving, and rendering templates in Alert Templates Settings
3. 3. Make sure all the users set up their Personal Notifications Settings on the Users Page