OneSignal

API

Push notification service and API, plus email, SMS and in-app messages

Price: Free tier, then paid
Access: App API key

About

OneSignal sends mobile and web push notifications, email, SMS and in-app messages through one REST API, client SDKs and a dashboard with Journeys automation. The free plan covers mobile push for up to 1,000 monthly active users and 10,000 emails a month.

What you can do with it

Send push notifications to iOS, Android and web browsers from your backend
Target users by segment, tag or external ID with one API call
Automate onboarding and re-engagement journeys across push, email and SMS

Get started

Create an app and add your FCM and APNs push credentials
Install the OneSignal SDK in your app
Copy the App ID and App API key

Example

curl -X POST "https://api.onesignal.com/notifications" \
  -H "Content-Type: application/json" \
  -H "Authorization: Key $ONESIGNAL_API_KEY" \
  -d '{"app_id":"YOUR_APP_ID","target_channel":"push","included_segments":["Subscribed Users"],"contents":{"en":"Hello, world"}}'

Details

Hosting: Hosted service
Available in: Worldwide
Official SDKs: JavaScript/TypeScript, Python, Java, Go, PHP, Ruby, C#, Rust, Swift, Kotlin, Dart
MCP server: Remote