n8n Workflow: Email Report for Overlapping Google Calendar Events

Automatically detect overlapping Google Calendar events and email yourself a clear report

This n8n workflow checks one Google Calendar for timed-appointment clashes, builds a plain-text overlap summary, and (in live mode) sends it via Gmail to the configured recipient—so you can fix scheduling conflicts fast.

What this workflow does

• Runs on demand or on a schedule (e.g., every morning) to keep your calendar reviewed automatically.
• Validates audit settings including calendar ID, recipient email, timezone, lookahead window, and report limits.
• Supports demo mode to generate fictional upcoming events so you can test everything without Google credentials. The included example produces a sample overlap.
• Fetches and expands events from Google Calendar in live mode, including recurring events, then prepares them for analysis.
• Filters events before checking overlaps by excluding cancelled, free (transparent), all-day, self-declined, and duplicate events.
• Detects overlapping timed appointments by finding overlapping event pairs with valid timed dates.
• Generates a text report with overlap counts, excluded events, and any events that could not be checked due to invalid timed dates.
• Sends the report via Gmail (live mode only) when attention is needed; otherwise it outputs results for inspection.

Use cases

• Prevent double-booking by automatically reviewing your team’s or personal calendar each morning.
• Run a no-credentials test first (demo mode), then switch to live mode to start alerting via email.
• Audit calendar data quality by highlighting events with invalid timed dates that can’t be reliably checked.

Technical details

• Integrations / nodes: Google Calendar, Gmail
• Workflow logic nodes: if, set, code, no op, sticky note
• Recurring event handling: expands recurring events during the audit window
• Report behavior: demo mode runs without sending email; live mode sends a Gmail report when attention is required