Firebase Cloud Messaging vs OneSignal

Firebase Cloud Messaging (FCM) delivers messages and notifications between servers and client devices over a reliable, battery-efficient connection. Senders can choose notification messages for display to users or data messages for an app to process. Messages can go to an individual device, groups of devices, or devices subscribed to topics; instant-messaging payloads can be up to 4096 bytes. Sending options include the Firebase Admin SDK, the FCM server protocol, and the Firebase console Notifications composer. Notification messages integrate with Google Analytics for engagement and conversion tracking, and A/B Testing with Remote Config supports testing notification variants. Setup guides cover Apple platforms, Android, web, Flutter, Unity, and C++. The JavaScript API works in browsers that support the Push API, including Chrome extensions using it. The web SDK requires HTTPS. FCM is free: its listed plan is free. Data in transit is protected with TLS, but FCM has no built-in end-to-end encryption; apps handling sensitive data must provide that protection themselves.

OneSignal is a messaging platform for reaching audiences through mobile and web push, email, in-app messaging, RCS, SMS and Live Activities. It also provides audience segmentation, automation, analytics and a visual journey builder. SDKs are available for Android, iOS, Flutter, React Native, Expo and Unity, and the service connects with analytics tools, customer data platforms, warehouses and CRMs. An API is included, with unlimited message-delivery API send access across plans. The Free plan costs $0 per month and includes all channels, basic automation and analytics, AI and MCP, and basic personalization. It includes 20,000 free email sends monthly; additional sends cost $1.50 per 1,000. Growth starts at $19 per month, plus usage fees, and is billed month-to-month. Professional and Enterprise use annual contracts with custom pricing. Growth customers can change plans or downgrade to Free at any time without penalty. OneSignal is available on web, Windows, macOS, iOS and Android.