OneSignal is a proprietary customer engagement platform combining push notifications, in-app messaging, email, and SMS. It has a usable free tier, but paid Growth plans charge per monthly active user across channels (for example per-MAU pricing on mobile push, plus per-message costs on email), and the platform itself is closed source and hosted entirely on OneSignal's infrastructure.
If you want multi-channel notification delivery without usage-based per-user fees or dependence on a single vendor's hosted service, Novu is the open-source, self-hostable alternative.
FAQ
Is there a free, open-source alternative to OneSignal?
Yes. Novu is open source and self-hostable, avoiding OneSignal's per-MAU and per-message pricing as your notification volume grows.
What's the best open-source alternative to OneSignal?
Novu is the closest match — one API covering push, email, SMS, and in-app notifications — with the option to self-host instead of paying usage-based fees indefinitely.
What are the top open-source alternatives to OneSignal?
Browse all open-source alternatives to OneSignal above, or explore the full Developer Tools category for more options.