Web Page Change Monitor with Gemini, Sheets & Slack Alerts

Monitor any web page for changes—get an automatic Gemini summary in Slack

This n8n automation checks a specified web page every 6 hours, saves cleaned snapshots in Google Sheets, and when the page text changes it uses Google Gemini to generate a short “what changed” summary and posts it to your Slack channel.

What this workflow does

• Runs on a 6-hour schedule to keep monitoring up to date.
• Fetches the configured URL using an HTTP Request. If the page can’t be retrieved, it sends a Slack alert for fetch failures.
• Extracts and cleans page text by stripping HTML down to plain text (limited to 6,000 characters) so comparisons are reliable.
• Stores and compares snapshots in Google Sheets: reads the last stored “Text” snapshot from a “Snapshots” sheet and compares it to the current cleaned text.
• Creates a baseline on the first run by saving the current page text to Google Sheets.
• Summarizes changes with Google Gemini when the text changes—providing a 2–3 sentence summary based on the previous and current versions.
• Posts to Slack and avoids repeat alerts: sends the summary plus the page link to your chosen Slack channel, then updates the snapshot in Google Sheets so the same change is only reported once.

Use cases

• Track updates on vendor pricing, documentation, or policy pages without manual checking.
• Monitor product landing pages or release notes for textual changes relevant to your SaaS operations.
• Alert your team in Slack when a critical web page becomes unavailable (fetch-failure notifications).

Technical details

• Schedule + control logic: if, set, code
• Web fetching: HTTP Request
• Change summarization: Google Gemini (PaLM) API
• Snapshot storage: Google Sheets (OAuth; “Snapshots” sheet with a Text column)
• Notifications: Slack (OAuth; alerts for both failures and change summaries)
• Helper notes: Sticky Note for workflow guidance

Set your label, URL, and CSS selector for the page section to monitor, pick your Google Sheet, ensure the “Snapshots” sheet exists, and choose the Slack channel for monitoring and alerts.