Free-tier messaging and notifications

Stream

Stream provides APIs and SDKs for building real-time chat messaging, video and audio calling, activity feeds, AI moderation, and Vision Agents. The platform includes shared infrastructure, prebuilt UI...

PubNub

PubNub is a real-time application platform that provides publish/subscribe messaging, message persistence, presence, file sharing, mobile push notifications, App Context, and serverless Functions. It ...

Knock

Knock is a customer engagement infrastructure platform for product, marketing, and transactional messaging. It provides workflows, broadcasts, guides, preferences, observability, and developer tooling for sending notifications across email, SMS, push, chat, and in-app channels.

Tencent RTC

Tencent RTC is a real-time communications platform that provides APIs and SDKs for voice, video, chat, live streaming, and related RTC features. The product page lists Call, Room, Live, Chat, Push, RT...

Ably is a realtime messaging platform that provides pub/sub APIs, chat, AI transport, live objects, spaces, and live sync for applications that need low-latency updates and state synchronization. The ...

Engagespot

Engagespot is a notification infrastructure platform for developers. It provides a single API for sending in-app, email, push, SMS, Slack, Discord, WhatsApp, and webhook notifications, along with templates, workflows, provider management, logging, and a built-in real-time in-app inbox.

Azure Event Grid

Azure Event Grid is a fully managed publish-subscribe message broker for real-time, event-driven, and serverless applications. It supports MQTT messaging, pull delivery, and push delivery so applications, Azure services, devices, and third-party systems can exchange discrete events and messages.

Pusher

Pusher provides hosted realtime APIs for building features such as live updates, pub/sub messaging, in-app chat, location tracking, and push notifications. Its Channels product supports publish/subscribe messaging across web and mobile clients, while Beams handles programmatic push notifications.

Azure Notification Hubs

Microsoft Azure Notification Hubs is a cross-platform push notification service for sending mobile notifications from any backend to iOS, Android, Windows, Kindle, and other connected devices. It supp...

Amazon SNS

Amazon Simple Notification Service (SNS) is a fully managed pub/sub messaging service from AWS that helps applications send notifications and distribute events at scale.