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This guide shows you how to receive real-time Google Calendar webhooks in Nango using notification channels. Unlike Gmail, Google Calendar does not require Google Cloud Pub/Sub—you configure a webhook URL directly with the Calendar API.

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How it works

The Google Calendar API uses notification channels to deliver webhooks. The flow is:
  1. You call the watch endpoint for the Google Calendar you want to monitor, passing your Nango webhook URL as the channel address.
  2. Google creates a notification channel and sends an initial sync message to your URL.
  3. When the watched calendar changes, Google sends a notification to Nango
  4. Nango matches the notification to the correct connection and forwards it to your app
Nango extracts the calendar owner from the X-Goog-Resource-URI header (e.g. .../calendars/user@example.com/events...) to match the webhook to a connection. For new connections, Nango persists only a hash of the user’s email (connection_config.emailAddressHash) automatically at connection time — no manual setup required.

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Setup

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1. Get your webhook URL

Copy the webhook URL from your Google Calendar integration page in the Nango dashboard, under the Webhook URL section. This is the HTTPS URL you will use as the channel address when creating notification channels.

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2. Create a notification channel (watch a resource)

Create a notification channel for the calendar you want to watch by sending a POST request to the appropriate watch endpoint. See the API reference for the exact URI. You can automate creating the channel for new connections with a post-connection-creation script: 
import { createOnEvent, ProxyConfiguration } from 'nango';
import { randomUUID } from 'crypto';
import z from 'zod';

export default createOnEvent({
    event: 'post-connection-creation',
    description: 'Create a Google Calendar notification channel for events on the primary calendar',
    metadata: z.object({
        googleCalendarChannelId: z.string().optional(),
        googleCalendarResourceId: z.string().optional(),
    }),
    exec: async (nango) => {
        const calResponse = await nango.get({
            baseUrlOverride: 'https://www.googleapis.com/calendar',
            endpoint: '/v3/users/me/calendarList/primary' 
        });

        const calendarEmail = calResponse.data.id; 
        const channelId = randomUUID();
        const expiration = Date.now() + 7 * 24 * 60 * 60 * 1000; // 7 days in ms
        const webhookUrl = await nango.getWebhookURL();

        const config: ProxyConfiguration = {
            baseUrlOverride: 'https://www.googleapis.com/calendar',
            endpoint: `/v3/calendars/${encodeURIComponent(calendarEmail)}/events/watch`,
            data: {
                id: channelId,
                type: 'webhook',
                // Webhook URL can be found on https://app.nango.dev/dev/integrations/google-calendar (your integration settings page)
                address: webhookUrl,
                expiration: expiration,
            },
        };

        const response = await nango.post(config);

        // Store channel info so it can be used to stop notifications later (step 4)
        await nango.updateMetadata({
            googleCalendarChannelId: channelId,
            googleCalendarResourceId: response.data.resourceId,
        });
    }
});
You can also do this manually: Example: watch the events collection on a calendar: 
curl -X POST "https://www.googleapis.com/calendar/v3/calendars/<CALENDAR_ID>/events/watch" \
  -H "Authorization: Bearer <AUTH_TOKEN>" \
  -H "Content-Type: application/json" \
  -d '{
    "id": "01234567-89ab-cdef-0123456789ab",
    "type": "web_hook",
    "address": "<REPLACE_WITH_NANGO_WEBHOOK_URL>",
    "expiration": <EXPIRATION>
  }'
Replace:
  • <CALENDAR_ID> — The calendar to watch, identified by the user’s email address.
  • <AUTH_TOKEN> — A valid OAuth 2.0 access token for the user who owns or has access to the calendar.
  • address — Your Nango webhook URL from the dashboard.
  • id — A unique string (e.g. UUID) identifying this channel; max 64 characters. It is echoed in X-Goog-Channel-ID on every notification.
  • expiration — (Optional) Unix timestamp in milliseconds when the channel should stop sending notifications. If omitted, Google applies a default; channels must be renewed before they expire.

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3. Renew the notification channel

Google does not renew channels automatically. When a channel is close to its expiration, you must create a new channel by calling the watch endpoint again with a new unique id. After the new channel is created successfully, stop the old channel so only one remains active. See Renew notification channels. You can use a Nango sync with a suitable frequency (e.g. every few days) to renew the watch before it expires: 
import { createSync, ProxyConfiguration } from 'nango';
import { randomUUID } from 'crypto';
import z from 'zod';

export default createSync({
    description: 'Renew the Google Calendar events watch channel before it expires',
    models: {},
    metadata: z.object({
        googleCalendarChannelId: z.string().optional(),
        googleCalendarResourceId: z.string().optional(),
    }),
    endpoints: [{ method: 'GET', path: '/google-calendar/watch-renewal' }],
    syncType: 'full',
    frequency: '1d',
    exec: async (nango) => {
        const metadata = await nango.getMetadata();
        const oldChannelId = metadata['googleCalendarChannelId'];
        const oldResourceId = metadata['googleCalendarResourceId'];

        const calResponse = await nango.get({
            baseUrlOverride: 'https://www.googleapis.com/calendar',
            endpoint: '/v3/users/me/calendarList/primary' 
        });

        const calendarEmail = calResponse.data.id; // This will be "user@company.com"
        const channelId = randomUUID();
        const expiration = Date.now() + 7 * 24 * 60 * 60 * 1000; // 7 days in ms
        const webhookUrl = await nango.getWebhookURL();

        const config: ProxyConfiguration = {
            baseUrlOverride: 'https://www.googleapis.com/calendar',
            endpoint: `/v3/calendars/${encodeURIComponent(calendarEmail)}/events/watch`,
            data: {
                id: channelId,
                type: 'webhook',
                // Webhook URL can be found on https://app.nango.dev/dev/integrations/google-calendar (your integration settings page)
                address: webhookUrl,
                expiration: expiration,
            },
        };

        const response = await nango.post(config);

        // Stop the old channel only after the new one was successful
        if (response.status === 200 && oldChannelId && oldResourceId) {
            try {
                await nango.post({
                    baseUrlOverride: 'https://www.googleapis.com/calendar',
                    endpoint: '/v3/channels/stop',
                    data: { id: oldChannelId, resourceId: oldResourceId },
                });
            } catch (err) {
                await nango.log(`Failed to stop previous channel: ${String(err)}`, { level: 'error' });
            }
        }

        // Update stored channel info for use in stop notifications (step 4)
        await nango.updateMetadata({
            googleCalendarChannelId: channelId,
            googleCalendarResourceId: response.data.resourceId,
        });
    }
});

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4. Stop notifications on connection deletion

If a connection is deleted in Nango but the channel remains active, Google may continue sending notifications until the channel expires. To stop notifications immediately for a deleted connection, call channels.stop before deletion. You can automate this with a pre-connection-deletion lifecycle event. This uses the googleCalendarChannelId and googleCalendarResourceId stored in metadata during channel creation (step 2) and renewal (step 3): 
import { createOnEvent, ProxyConfiguration } from 'nango';

export default createOnEvent({
    event: 'pre-connection-deletion',
    description: 'Stop Google Calendar notification channel before connection deletion',
    exec: async (nango) => {
        const metadata = await nango.getMetadata();
        const channelId = metadata['googleCalendarChannelId'];
        const resourceId = metadata['googleCalendarResourceId'];

        if (!channelId || !resourceId) {
            return;
        }

        const config: ProxyConfiguration = {
            baseUrlOverride: 'https://www.googleapis.com/calendar',
            endpoint: '/v3/channels/stop',
            data: {
                id: channelId,
                resourceId
            }
        };

        try {
            await nango.post(config);
        } catch (err) {
            // Avoid blocking connection deletion if stop fails.
            await nango.log(`Failed to stop Calendar channel: ${String(err)}`, { level: 'error' });
        }
    }
});

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5. Handle forwarded webhooks

When a Calendar notification arrives, Nango matches it to the correct connection and forwards it to your system. Notification messages have no body; Google sends only HTTP headers. Nango forwards those headers in the payload. Example structure: 
{
  "from": "google-calendar",
  "providerConfigKey": "google-calendar",
  "type": "forward",
  "payload": {
    "x-goog-channel-id": "01234567-89ab-cdef-0123456789ab",
    "x-goog-resource-id": "o3hgv1538sdjfh",
    "x-goog-resource-uri": "https://www.googleapis.com/calendar/v3/calendars/user@example.com/events",
    "x-goog-resource-state": "exists",
    "x-goog-message-number": "10"
  },
  "connectionId": "connection-123"
}
Relevant headers (see Google’s documentation):
HeaderDescription
x-goog-resource-statesync = channel created; exists = resource changed (create/update/delete).
x-goog-resource-uriThe watched resource (e.g. which calendar’s events).
x-goog-channel-idThe channel id you sent when creating the channel.
x-goog-message-numberIncrementing message number for this channel.
Notifications do not include the changed events themselves—you must call the Calendar API (e.g. list events or get event) to fetch the updates. After receiving the webhook, trigger your sync or API calls for that connection: 
curl -X POST "https://api.nango.dev/sync/trigger" \
  -H "Authorization: Bearer <NANGO_SECRET_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "sync_mode": "incremental",
    "connection_id": "<CONNECTION_ID>",
    "provider_config_key": "google-calendar",
    "syncs": ["events"]
  }'
With webhooks driving real-time updates, you can run syncs less often (e.g. 1d or 1h) as a safety net for missed notifications.
If you prefer Nango to automatically run a sync when the webhook arrives (instead of forwarding it to your app), you can enable webhook processing in a sync script using webhookSubscriptions and onWebhook. For Google Calendar, subscribe to '*' and use the forwarded headers (e.g. x-goog-resource-state, x-goog-resource-uri) to decide what to fetch.See: Real-time syncs

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Connection matching

Nango matches the incoming request to a connection using the calendar identifier (email) extracted from X-Goog-Resource-URI (e.g. .../calendars/user@example.com/events...). The lookup order is:
  1. connection_config.emailAddressHash — automatically set by Nango for new connections (created after 2026-03-11)
  2. metadata.emailAddress — fallback (customer-controlled)
  3. metadata.email — fallback (customer-controlled)
For new connections (created after 2026-03-11), no action is needed. Nango automatically persists the email hash at connection time. For existing connections created before this feature was available, you have two options:
  • Re-authorize the connection so Nango’s post-connection hook runs and persists the email hash automatically
  • Set the metadata manually via the API:
curl -X PATCH "https://api.nango.dev/connection/metadata" \
  -H "Authorization: Bearer <NANGO_SECRET_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "connection_id": "<CONNECTION_ID>",
    "provider_config_key": "google-calendar",
    "metadata": {"emailAddress": "<USER_EMAIL>"}
  }'
To do this in bulk, iterate over the list connections response and update the metadata for each one.
If Nango cannot match the incoming webhook to a connection (because it can’t find a matching hash/email in connection_config or metadata), the webhook will still be received but won’t include a connectionId in the forwarded payload.

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Rollback strategy

To stop webhooks:
  1. Call channels/stop for each channel you created (using the channel id and resourceId), or
  2. Let the channel expire by not renewing it.
Re-enable notifications by creating a new channel with a new id and your Nango webhook URL as address.
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