Customer Engagement Platform for Email, Push… - OneSignal

> Full documentation index, SDK/API links, and AI usage guidelines: [llms-full.txt](https://onesignal.com/llms-full.txt) # OneSignal OneSignal is a lifecycle customer engagement platform. It helps product, marketing, and engineering teams drive activation, retention, and revenue through orchestrated messaging across mobile push, web push, email, SMS/RCS, in-app messaging, and iOS Live Activities—delivering personalized, real-time experiences from onboarding to re-engagement at global scale. ## Scale (onesignal.com homepage) * **1 in 4** — App publishers use OneSignal * **1.3 trillion** — Messages sent a year * **1.5 billion** — MAU powered by OneSignal * **200k** — Apps powered by OneSignal ## Product ### Messaging Channels * Mobile push: https://onesignal.com/mobile-push * Web push: https://onesignal.com/web-push * Email: https://onesignal.com/email * SMS & RCS: https://onesignal.com/rcs * In-app messaging: https://onesignal.com/in-app * Live Activities: https://onesignal.com/live-activities ### Lifecycle & Automation * Journeys (automation): https://onesignal.com/journeys * Event-based messaging & triggers (Journeys): https://documentation.onesignal.com/docs/en/journeys-overview * User segmentation: https://documentation.onesignal.com/docs/en/segmentation ### Personalization & Data * User profiles & data: https://documentation.onesignal.com/docs/en/users * Tags & dynamic content: https://documentation.onesignal.com/docs/en/add-user-data-tags ### Analytics & Optimization * Message analytics: https://documentation.onesignal.com/docs/en/analytics-overview * Outcomes tracking: https://documentation.onesignal.com/docs/en/custom-outcomes * A/B testing: https://documentation.onesignal.com/docs/en/ab-testing ## Use Cases * User activation & onboarding * Lifecycle messaging & retention * Churn prevention & re-engagement * Transactional notifications * Promotions & announcements * Personalization at scale ## Why OneSignal * Unified platform across