Slack uptime alerts

Updated 25 October 2026 · By the Upcertain team

Create the incoming webhook in Slack

1. In Slack, open Apps and add Incoming Webhooks (or open your own Slack app's Incoming Webhooks page and turn it on).
2. Choose the channel the alerts should go to, for example #ops-alerts.
3. Copy the webhook URL. It starts with https://hooks.slack.com/services/.

Slack fixes the channel when the webhook is created. To alert a second channel, create a second webhook and add it as a second Upcertain channel.

Add it in Upcertain

1. In Upcertain, open Settings, Alert channels and choose Slack. Owners, admins and editors can add channels.
2. Paste the webhook URL. Add the channel name (#ops-alerts) as a label so your team can tell channels apart; Slack decides the actual channel.
3. Pick the events to send: Down, Up (recovery) and SSL certificate expiry.
4. Tick Pre-select on new monitors if this should be the default for monitors you create from now on. Existing monitors keep their own choice.
5. Save, then use Send a test in the channel list to post a test message.
6. Open each monitor that should alert here and add the channel under its alert settings, with an optional delay and repeat interval.

What a Slack alert looks like

• Down: the monitor's name and address, the cause (for example HTTP 503, a timeout or a missing keyword), when it started, and buttons to acknowledge or view the incident.
• Still down: a reminder with the time so far, if you set a repeat interval on the monitor's channel (every 5 to 1440 minutes). Acknowledging the incident stops reminders.
• Up: the recovery with the cause and the total downtime, in the same channel.
• SSL certificate expiry: a warning on the days you chose before a certificate expires.
• Grouped alert: if alert grouping is on and several monitors fail within a few minutes, one message lists them all instead of one message each.

Messages use Slack's colour bar (red for down, green for up, amber for SSL warnings), so the channel reads at a glance. Monitor names are escaped, so a name cannot mention @channel or hide a link.

Acknowledging from Slack

The Acknowledge button opens the incident in Upcertain, where a signed-in owner, admin or editor confirms it. Acknowledging stops reminders on every channel and records who took it. The recovery message follows in the same channel when the monitor is up again; Upcertain does not use threads.

Keeping the channel useful

• Route by owner: payments monitors to #payments-oncall, marketing sites to #web. Each monitor picks its own channels.
• Use confirmation checks so a single dropped request never posts.
• Delay a channel by a few minutes for services where a short blip is not worth a message, and keep email or a second channel immediate.
• Turn on alert grouping (Settings, owners and admins) so an outage of a shared dependency posts one message, not twenty.