Sync workflow schedules between Google Sheets and Google Calendar

Description

Sync n8n Workflow Schedules to Google Calendar

Reads every workflow on your n8n instance every 30 minutes, extracts their schedule triggers, and keeps a matching recurring event on Google Calendar — one event per workflow, forever in sync.

How it works

Schedule Trigger (30 min)
→ GET /api/v1/workflows — fetch all workflows
→ Code: parsing — extract scheduleTrigger / cron nodes
→ Sheets: Lookup — read saved state (schedule, On Calendar, EventID)
→ Code: detect changes — create / update / skip
├─ create → build RRULE payload → Create event → write EventID to Sheets
└─ update → delete old event (parallel) + create new event → write to Sheets

State is stored in a Google Sheets tab (n8n Scheduling). The sheet acts as the single source of truth between runs.

What gets a Calendar event

| Schedule type | Result |
| -------------------------------------- | ---------------------------------------------------------- |
| Daily | DAILY recurring event |
| Weekly (with or without specific days) | WEEKLY recurring event |
| Monthly | MONTHLY recurring event |
| Hourly | 1 DAILY event at 00:MM (not 24 — avoids GCal rate limit) |
| Cron / minutely | Skipped — not supported by Google Calendar RRULE |
| This workflow itself | Always skipped |

Prerequisites

n8n instance with API enabled
Google Cloud project with:
Service Account (for Sheets — never expires)
OAuth 2.0 client (for Google Calendar — expires periodically)
A Google Sheets spreadsheet shared with the Service Account
A Google Calendar to write events to

Credentials

| n8n credential type | Used for |
| -------------------------- | ------------------------------------------ |
| n8n API | Reading the workflow list |
| Google Calendar OAuth2 API | Creating / deleting Calendar events |
| Google Service Account | Reading and writing the Sheets state store |

> ⚠️ The Google Calendar OAuth2 credential expires. Reconnect it from Settings → Credentials when Calendar nodes start failing.

Setup

Full step-by-step setup in documentation.md.

Known limits

OAuth token expiry breaks sections D/E silently — set up the error workflow to get notified
Hourly schedules map to a single daily event (label includes ogni ora :MM)
The disconnected Webhook sub-flow (section F) is a manual maintenance utility — not part of the main pipeline