Database

"Ably: real-time messaging, pub/sub, presence, message history, push notifications, WebSocket/SSE"

"Knock: notification infrastructure, in-app feeds, workflows, preferences, channels, React components"

"Novu: notification infrastructure, multi-channel (email/SMS/push/in-app), templates, preferences, digest, workflows"

"OneSignal: push notifications, in-app messaging, email, SMS, segments, journeys, REST API"

"Pusher: real-time WebSocket channels, presence channels, private channels, triggers, React hooks"

"Sendbird: chat SDK, group channels, open channels, messages, file sharing, moderation, UIKit components"

"Stream (GetStream): chat SDK, channels, threads, reactions, typing indicators, moderation, React components"

"Twilio: SMS, voice calls, WhatsApp, verify API, programmable messaging, webhooks, Node SDK"