OneSignal
FreemiumUntestedOur check runs without a key, so we couldn't test this one. It doesn't mean it's down.
Send push, email, SMS and in-app messages from one REST API, with segmentation and delivery data.
Example request
curl -X POST https://api.onesignal.com/notifications -H 'Content-Type: application/json' -H 'Authorization: Key $API_KEY' -d '{"app_id":"YOUR_APP_ID","target_channel":"push","included_segments":["Subscribed Users"],"contents":{"en":"Hello, world"}}'Free tier, in plain English
Free plan covers all channels at small scale: 10k emails/month and unlimited push/in-app under 1,000 monthly active users.