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Push notification API (coming soon)

Centrifugo excels in delivering real-time in-app messages to online users. Sometimes though you need a way to engage offline users to come back to your app. Or trigger some update in the app while it's running in the background. That's where push notifications may be used. Push notifications delivered over battery-efficient platform-dependent transport.

With Centriufugo PRO push notifications may be delivered to all popular application platforms:

  • Android devices
  • iOS devices
  • Web browsers which support Web Push API (Chrome, Firefox, see this matrix)

Centrifugo PRO provides API to manage user device tokens, device channel subscriptions and API to send push notifications towards registered devices and group of devices (subscribed to a channel).


To deliver push notifications to devices Centrifugo PRO integrates with the following providers:

This means that Centrifugo PRO covers full flow of sending push notifications including frontend SDKs (provided by FCM, HMS, Apple SDKs).

All these push notification providers only manage frontend and transport part of notification delivery. Device token management and effective push notification broadcasting are parts to be solved by the application backend. Centrifugo PRO provides an API to store tokens in database (PostgreSQL), manage device subscriptions to channels in a unified way.

Centrifugo PRO comes with worker queues (based on Redis streams) which allow broadcasting push notifications towards devices in a very efficient way.

Integration with FCM means that you can use existing Firebase messaging SDKs to extract push notification token for a device on different platforms (iOS, Android, Flutter, web browser) and setting up push notification listeners. Only a couple of additional steps required to integrate frontend with Centrifugo PRO device token and device subscription storage. After doing that you will be able to send push notification towards single device, or towards devices subscribed to a channel. For example, with a simple Centrifugo API call like this:

curl -X POST http://localhost:8000/api \
-H "Authorization: apikey <KEY>" \
-d @- <<'EOF'

"method": "send_push_notification",
"params": {
"recipient": {"channels": ["test"]},
"notification": {
"fcm": {
"message": {
"notification": {"title": "Hello", "body": "How are you?"}

Motivation and design choices

Usually the first thing you'd do in the app to start delivering push notifications is integrating with huge providers like FCM, HMS, APNs. Integrating with these providers usually mean you need to keep device tokens in the application database and implement sending push messages to provider Push Services.

Centrifugo PRO provides the required backend for device tokens, and tries to follow best practices when working with tokens. It follows provider advices to keep only a working set of device tokens by reacting on errors and periodically removing stale devices/tokens.

Centrifugo PRO provides an efficient and scalable queuing mechanism for sending push notifications. Developers can send notifications from the app backend to Centrifugo API with a minimal latency, and let Centrifugo process sending to FCM, HMS, APNs concurrently from the built-in workers.

FCM and HMS have a built-in way of sending notification to large groups of devices over topics mechanism (the same for HMS). One problem with native FCM or HMS topics though is that client can subscribe to any topic from the frontend side without any permission check. In today's world this is usually not desired. So Centrifugo PRO re-implements FCM, HMS topics by introducing an additional API to manage device subscriptions to channels. We intentionally called it channels to make the concept closer to our real-time API. In some cases you may have real-time channels and device subscription channels with matching names – to send messages to both online and offline users. Though it's up to you. Centrifugo PRO device subscriptions also add a way to introduce topic semantics for APNs.

Centrifugo PRO tries to avoid combining push notifications APIs for all supported providers into one unified API – just gives a way to send notification payloads in a format defined by each provider. This allows Centrifugo PRO to be a non-obtrusive proxy for all the mentioned providers.

Apart from this you get a possibility to inspect sent push notifications over our ClickHouse analytics. Also, providers may provide their own analytics. For example, FCM provides analytics from which you can get insight into push notification delivery.

One more thing – in our push API we left a possibility to send notifications into FCM, HMS topics or sending to raw FCM, HMS, APNs tokens, so you can combine native provider primitives with those added by Centrifugo (i.e. sending to a list of device IDs or to a list of channels).

Steps to integrate

  1. Add provider SDK on the frontend side, follow provider instructions for your platform to obtain a push token for a device. For example, for FCM see instructions for iOS, Android, Flutter, Web Browser). The same for HMS or APNs – frontend part should be handled by their native SDKs.
  2. Call Centrifugo PRO backend API with the obtained token. From the application backend call Centrifugo device_register API to register the device in Centrifugo PRO storage.
  3. Centrifugo returns a registered device object, pass a generated device ID to the frontend and save it on the frontend together with a token received from FCM.
  4. Subscribe device to the required set of channels, first by calling your backend with device ID and list of channels, check channel permissions and then call Centrifugo device_subscription_set or device_subscription_add APIs.
  5. Call Centrifugo send_push_notification API whenever it's time to deliver a push notification.

At any moment you can inspect device and subscription storage by calling device_list or device_subscription_list APIs.

Also, you can remove unnecessary by using device_remove or device_subscription_remove APIs.


In Centrifugo PRO you can configure one push provider or use all of them – this choice is up to you.


As mentioned above Centrifigo uses PostgreSQL for token storage. To enable push notifications make sure database section defined in the configration and fcm is in the push_notifications.enabled_providers list. Centrifugo PRO uses Redis for queuing push notification requests, so Redis address should be configured also. Finally, to integrate with FCM a path to the credentials file must be provided (see how to create one in this instruction). So the full configuration to start sending push notifications over FCM may look like this:

"database": {
"dsn": "postgresql://postgres:[email protected]:5432/postgres"
"push_notifications": {
"redis_address": "localhost:6379",
"enabled_providers": ["fcm"],
"fcm_credentials_file_path": "/path/to/service/account/credentials.json"

Actually, PostgreSQL database configuration is optional here – you can use push notifications API without it. In this case you will be able to send notifications to FCM, HMS, APNs raw tokens, FCM and HMS native topics and conditions. I.e. using Centrifugo as an efficient proxy for push notifications (for example if you already keep tokens in your database). But sending to device ids and channels, and token/subscription management APIs won't be available for usage.


"database": {
"dsn": "postgresql://postgres:[email protected]:5432/postgres"
"push_notifications": {
"redis_address": "localhost:6379",
"enabled_providers": ["hms"],
"hms_app_id": "<your_app_id>",
"hms_app_secret": "<your_app_secret>",

See example how to get app id and app secret here.


"database": {
"dsn": "postgresql://postgres:[email protected]:5432/postgres"
"push_notifications": {
"redis_address": "localhost:6379",
"enabled_providers": ["apns"],
"apns_endpoint": "development",
"apns_bundle_id": "com.example.your_app",
"apns_auth": "token",
"apns_token_auth_key_path": "/path/to/auth/key/file.p8",
"apns_token_key_id": "<your_key_id>",
"apns_token_team_id": "your_team_id",

We also support auth over p12 certificates with the following options:

  • push_notifications.apns_cert_p12_path
  • push_notifications.apns_cert_p12_b64
  • push_notifications.apns_cert_p12_password

Other options


This option configures the number of days to keep device without updates. By default Centrifugo does not remove inactive devices.

API description


Registers or updates device information.

device_register request

idstringNoID of the device being registered (only provide when updating).
providerstringYesProvider of the device token (valid choices: fcm, hms, apns).
tokenstringYesPush notification token for the device.
platformstringYesPlatform of the device (valid choices: ios, android, web).
userstringNoUser associated with the device.
metamap<string, string>NoAdditional metadata for the device (not indexed).
tagsmap<string, string>NoAdditional tags for the device (indexed data).
channelsarray of stringsNoDevice channel subscriptions.

device_register result

Field NameTypeDescription
deviceDeviceThe device that was registered.


Field NameTypeDescription
idstringThe device's ID.
providerstringThe device's token provider.
tokenstringThe device's token.
platformstringThe device's platform.
userstringThe user associated with the device.


Call this method to update device. For example, when user logs out the app and you need to detach user ID from the device.

device_update request


device_update result



Removes device from storage. This may be also called when user logs out the app and you don't need its device token after that.

device_remove request

Field NameTypeRequiredDescription
idsrepeated stringNoA list of device IDs to be removed
usersrepeated stringNoA list of device user IDs to filter devices to remove
provider_tokensProviderTokensNoProvider tokens to remove

device_remove result

Empty object.


Returns a paginated list of registered devices according to request filter conditions.

device_list request

idsrepeated stringNoList of device IDs to filter results.
providersrepeated stringNoList of device token providers to filter results.
tokensrepeated stringNoList of device tokens to filter results.
platformsrepeated stringNoList of device platforms to filter results.
usersrepeated stringNoList of device users to filter results.
sincestringNoCursor for pagination (last device id in previous batch).
limitint32NoMaximum number of devices to retrieve.
include_metaboolNoFlag indicating whether to include meta information for each device.

device_list result

Field NameTypeDescription
itemsrepeated DeviceA list of devices
has_moreboolA flag indicating whether there are more devices available


Manage mapping of channels with users. These user channels will be automatically attached to user devices upon registering.

push_user_channel_update request


push_user_channel_update result



List user to channel mapping.

push_user_channel_list request


push_user_channel_list result



Send push notification to specific device_ids, or to channels, or native provider identifiers like fcm_tokens, or to fcm_topic. Request will be queued by Centrifugo, consumed by Centrifugo built-in workers and sent to the provider API.

send_push_notification request

Field nameTypeRequiredDescription
recipientPushRecipientYesRecipient of push notification
notificationPushNotificationYesPush notification to send

PushRecipient (you must set only one of the following fields):

device_idsrepeated stringNoSend to a list of device IDs
channelsrepeated stringNoSend to channels
fcm_tokensrepeated stringNoSend to a list of FCM tokens
fcm_topicstringNoSend to a FCM topic
fcm_conditionstringNoSend to a FCM condition
hms_tokensrepeated stringNoSend to a list of HMS tokens
hms_topicstringNoSend to a HMS topic
hms_conditionstringNoSend to a HMS condition
apns_tokensrepeated stringNoSend to a list of APNs tokens


fcmFcmPushNotificationNoNotification for FCM
hmsHmsPushNotificationNoNotification for HMS
apnsApnsPushNotificationNoNotification for APNs
uidstringNoUnique send id
expire_atint64NoUnix timestamp when Centrifugo stops attempting to send this notification (this does not relate to notification TTL fields)


messageJSON objectYesFCM Message described in FCM docs.


messageJSON objectYesHMS Message described in HMS Push Kit docs.


headersmap<string, string>NoAPNs headers
payloadJSON objectYesAPNs payload

send_push_notification result

Field NameTypeDescription
uidstringUnique send id, matches uid in request if it was provided

Proto definitions


Several metrics are available to monitor the state of Centrifugo push worker system:

  • centrifugo_push_notification_count - counter, shows total count of push notifications sent to providers (splitted by provider, recipient type, platform, success, error code).
  • centrifugo_push_queue_consuming_lag - gauge, shows the lag of queues, should be close to zero most of the time. Splitted by provider and name of queue.
  • centrifugo_push_consuming_inflight_jobs - gauge, shows immediate number of workers proceccing pushes. Splitted by provider and name of queue.
  • centrifugo_push_job_duration_seconds - summary, provides insights about worker job duration timings. Splitted by provider and recipient type.


Coming soon.