n8n Workflow: Slack Alerts for Stale Heartbeats (Google Sheets)

Slack alerts for stale workflow heartbeats—automatically, every 15 minutes

This n8n workflow checks heartbeat timestamps stored in Google Sheets and sends a Slack alert whenever a monitored workflow has missing/invalid last-success data or is overdue based on its configured maximum age.

What this workflow does

• Runs on a schedule every 15 minutes using an n8n schedule trigger.
• Reads heartbeat data from a Google Sheets tab named heartbeats, with columns:
  • workflow
  • last_success
  • max_age_minutes
• Calculates heartbeat age for each row and flags workflows when:
  • last_success is missing or invalid, or
  • the timestamp is older than max_age_minutes.
• Builds a detailed Slack message for every stale workflow, including the last success age, the expected success interval, and the reason for the alert.
• Sends alerts to the selected Slack channel via the Slack node.

Use cases

• Monitor critical n8n automations and get notified if a workflow hasn’t succeeded within an expected window.
• Detect failures early when last_success is missing/invalid in your heartbeats sheet.
• Give SaaS operations teams quick visibility in Slack when scheduled processes fall behind.

Technical details

• Schedule trigger: executes every 15 minutes.
• Google Sheets: reads the heartbeats table (sheet/tab name must be heartbeats).
• Code: computes heartbeat age and decides whether each workflow is stale.
• Slack: posts alerts to your chosen channel.
• Sticky note: included for workflow guidance/documentation.

Setup (high level)

• Create the Google Sheet tab heartbeats with workflow, last_success, and max_age_minutes.
• Add Google Sheets credentials in n8n and set your YOUR_SHEET_ID in the Google Sheets node.
• Add Slack credentials, select the channel, and ensure each monitored workflow updates its row after real work succeeds by writing the current ISO timestamp to last_success and the expected interval to max_age_minutes.