Monitor website uptime and content changes with HTTP checks and Slack

Description

Quick Overview
This workflow runs every 30 minutes to check a list of website URLs, detect downtime or page content changes using HTTP requests and stored workflow state, and post alerts to a Slack channel only when something goes down, changes, or recovers.

How it works
Runs every 30 minutes on a schedule.
Builds a list of target URLs (with labels) to monitor.
Fetches each page with an HTTP GET request while capturing the full response and continuing even on 4xx/5xx errors.
Compares each page’s current status code and content signature against the last saved value in n8n workflow static data and updates the stored baseline.
Posts a message to Slack only when a page is down, its content has changed, or it has recovered.

Setup
Add a Slack credential/connection and set the destination channel (for example, #alerts).
Update the URL list (label and url fields) in the “Define URLs to Monitor” code step.
Optionally adjust the schedule interval and HTTP timeout to match your monitoring needs.