Notification Channels

A notification channel is a destination where Holter sends alerts. Each channel belongs to a workspace and can be linked to multiple monitors.

Creating a Channel

1. Click Channels in the left sidebar.
2. Click New Channel.
3. Fill in the fields below and click Create Channel.

Fields

Field	Required	Description
Name	Yes	A human-readable label for the channel (e.g. "Ops Webhook").
Type	Yes	One of: webhook, email.
Target	Yes	The delivery destination. See format rules by type below.

Target format by type

Type	Expected format
webhook	A valid http:// or https:// URL.
email	A valid email address (e.g. [email protected]).

Editing a Channel

Click the channel name in the Channels list (/delivery/workspaces/{workspace_slug}/channels) to open its settings page at /delivery/notification-channels/{id}. You can update the name and target. The channel type cannot be changed after creation.

Sending a Test Notification

On the channel settings page, click Send Test to enqueue a test notification. The test payload includes the channel name and a timestamp. This is useful to verify that the target is reachable before linking the channel to a monitor.

Deleting a Channel

On the channel list page, click Delete next to the channel. This removes the channel and all monitor links. Monitors linked to a deleted channel will no longer receive notifications for that channel.

Linking Channels to Monitors

Channels own the link to monitors. To connect a channel to one or more monitors:

1. Open the channel settings page.
2. In the Linked Monitors section, check each monitor that should trigger notifications through this channel.
3. Click Save Changes.

Unchecking a monitor and saving immediately stops future notifications for that monitor through this channel.

You can also manage links via the API — include a notification_channel_ids array in the monitor create or update request body.

Payload Shape

When a monitor goes down or recovers, Holter sends the following JSON payload to webhook channels:

{
  "version": "1",
  "event": "monitor_down",
  "timestamp": "2026-04-20T10:00:00Z",
  "monitor": {
    "id": "...",
    "url": "https://example.com",
    "method": "get"
  },
  "incident": {
    "id": "...",
    "type": "downtime",
    "started_at": "2026-04-20T10:00:00Z",
    "resolved_at": null
  }
}

Events: monitor_down, monitor_up. For SSL expiry incidents the event is ssl_expiry_down / ssl_expiry_up.

Related

• Monitoring module — incidents that trigger delivery
• API reference — REST endpoints for notification channels