Calendar

Seshn + Google Calendar

Automatically sync bookings to Google Calendar — create events on booking, update on reschedule, remove on cancel.

Install

1npm install googleapis

Webhook events

Map booking lifecycle events to calendar operations:

booking.createdCreate a calendar event

booking.confirmedUpdate event status to confirmed

booking.rescheduledMove event to new time

booking.cancelledDelete the calendar event

booking.series_createdCreate a recurring calendar event

Setup

Use a Google Cloud service account for server-to-server calendar access. This avoids OAuth flows in your webhook handler.

Create a project in the Google Cloud Console.
Enable the Google Calendar API.
Create a service account and download the JSON key.
Share your staff calendar with the service account email.

Webhook handler

app/api/webhooks/seshn/route.ts

1import { google } from 'googleapis';
2import { createHmac } from 'crypto';
3
4const WEBHOOK_SECRET = process.env.SESHN_WEBHOOK_SECRET!;
5const CALENDAR_ID = process.env.GOOGLE_CALENDAR_ID!;
6
7const auth = new google.auth.GoogleAuth({
8  keyFile: process.env.GOOGLE_SERVICE_ACCOUNT_KEY_PATH,
9  scopes: ['https://www.googleapis.com/auth/calendar'],
10});
11
12const calendar = google.calendar({ version: 'v3', auth });
13
14export async function POST(req: Request) {
15  const body = await req.text();
16  const signature = req.headers.get('x-webhook-signature');
17
18  const expected = 'sha256=' +
19    createHmac('sha256', WEBHOOK_SECRET).update(body).digest('hex');
20
21  if (signature !== expected) {
22    return new Response('Invalid signature', { status: 401 });
23  }
24
25  const event = req.headers.get('x-webhook-event');
26  const payload = JSON.parse(body);
27
28  switch (event) {
29    case 'booking.created':
30    case 'booking.confirmed':
31      await calendar.events.insert({
32        calendarId: CALENDAR_ID,
33        requestBody: {
34          summary: `${payload.service.name} — ${payload.contact.name}`,
35          description: `Booking ${payload.id}\n${payload.seats} seat(s)`,
36          start: {
37            dateTime: payload.slot.startTime,
38            timeZone: payload.location.timezone,
39          },
40          end: {
41            dateTime: payload.slot.endTime,
42            timeZone: payload.location.timezone,
43          },
44          // Use booking ID as event ID for easy lookup later
45          id: payload.id.replace(/-/g, '').slice(0, 32),
46        },
47      });
48      break;
49
50    case 'booking.rescheduled':
51      const eventId = payload.id.replace(/-/g, '').slice(0, 32);
52      await calendar.events.patch({
53        calendarId: CALENDAR_ID,
54        eventId,
55        requestBody: {
56          start: {
57            dateTime: payload.newSlot.startTime,
58            timeZone: payload.location.timezone,
59          },
60          end: {
61            dateTime: payload.newSlot.endTime,
62            timeZone: payload.location.timezone,
63          },
64        },
65      });
66      break;
67
68    case 'booking.cancelled':
69      await calendar.events.delete({
70        calendarId: CALENDAR_ID,
71        eventId: payload.id.replace(/-/g, '').slice(0, 32),
72      }).catch(() => {
73        // Event may not exist — that's ok
74      });
75      break;
76  }
77
78  return new Response('OK', { status: 200 });
79}

Register the webhook

terminal

1curl -X POST https://api.seshn.net/v1/webhooks \
2  -H "Authorization: Bearer sk_live_..." \
3  -H "Content-Type: application/json" \
4  -d '{
5    "url": "https://yourdomain.com/api/webhooks/seshn",
6    "events": [
7      "booking.created",
8      "booking.confirmed",
9      "booking.rescheduled",
10      "booking.cancelled",
11      "booking.series_created"
12    ]
13  }'

Next steps

Add attendees to the event to send Google Calendar invites to customers automatically.
For booking.series_created, use Google Calendar's recurrence rules (RRULE) instead of individual events.
Store the Google Calendar event ID in Seshn booking metadata for two-way sync.