# Realtime **Canonical:** https://apis.io/providers/realtime/ **APIs profiled:** 26 A topic catalog of realtime APIs, protocols, providers, and patterns. Realtime distinguishes itself from streaming by being interactive and typically bidirectional — channels, presence, signaling, and message envelopes flowing in both directions between clients and servers — where streaming is one-way firehose delivery. This index documents the major realtime protocols (WebSocket, Server-Sent Events, WebRTC, MQTT, CoAP, gRPC streaming, GraphQL Subscriptions), hosted realtime providers (Ably, Pusher, PubNub, LiveKit, Daily, Agora, Twilio, Vonage, Amazon IVS, Cloudflare Realtime), open-source frameworks (Socket.IO), and push notification systems (OneSignal, FCM, APNs, Web Push, Pushwoosh). ## Kin Score — 15.9 / 100 (emerging) Scored 2026-08-21 under rubric 0.12.0. Trend: flat (+0.0 from 15.9). | Facet | Score | |---|---| | Discoverability | 64.8 | | Contract Quality | 16.9 | | Governance | 25.0 | | Contract Governance | 25.0 | | Operational Transparency | 2.6 | | Developer Ergonomics | 9.5 | | Commercial Clarity | 0.0 | | Access Clarity | 0.0 | ## Agent readiness — 1.5 (human-only) | Dimension | Value | |---|---| | Spec Presence | no | | Agentic Access | no | | Reversibility Documented | no | | MCP Server | no | | Auth Clarity | no | | Idempotency | no | | Error Semantics | no | | OpenAPI Examples | documented | | Rate Limit Signal | no | | Event Surface Described | no | | Agent Skills | no | | Well Known Catalog | no | | Consent Identity | no | | Agent Card | no | | Dry Run Mode | no | ## Access Unknown — onboarding: unknown, pricing: unknown, trial: no (confidence: low). ## APIs (26) - **WebSocket** — A full-duplex communication protocol over a single TCP connection, standardized by the IETF as RFC 6455 and defined in the WHATWG WebSocket API on the client side. WebSocket is ... - **Server-Sent Events (SSE)** — A unidirectional server-to-client streaming protocol over HTTP, defined by the WHATWG HTML Living Standard. SSE is simpler than WebSocket — it reuses HTTP and supports automatic... - **WebRTC** — A peer-to-peer realtime communication framework for audio, video, and arbitrary data channels, standardized by the W3C and IETF. WebRTC defines an SDP-based offer/answer signali... - **MQTT** — A lightweight publish/subscribe protocol standardized by OASIS, designed for constrained devices and low-bandwidth networks. MQTT is the dominant realtime protocol in IoT, used ... - **CoAP** — The Constrained Application Protocol, defined in IETF RFC 7252, is a RESTful protocol for constrained devices over UDP, with an Observe extension (RFC 7641) that provides realti... - **gRPC Streaming** — gRPC supports four call patterns — unary, server streaming, client streaming, and bidirectional streaming — all carried over HTTP/2. gRPC streams are widely used for internal se... - **GraphQL Subscriptions** — A GraphQL operation type that delivers realtime updates to clients, typically carried over WebSocket using the graphql-ws or legacy graphql-transport-ws protocol, or over SSE us... - **WebTransport** — A modern web API built on HTTP/3 and QUIC providing bidirectional and unidirectional streams plus unreliable datagrams to browsers. Designed as a higher-performance successor to... - **Ably** — A hosted realtime platform offering Pub/Sub Channels, Chat, Spaces, LiveObjects, LiveSync, and AI Transport — built on a global edge network with low-latency multiprotocol fanou... - **PubNub** — A realtime platform offering Pub/Sub messaging, Presence detection, Chat SDKs, Functions (serverless), Events & Actions, Insights analytics, BizOps Workspace, Illuminate, and an... - **Pusher** — A hosted realtime API from MessageBird offering two products — Channels (pub/sub messaging) and Beams (push notifications) — under the framing "Our hosted APIs are flexible, sca... - **LiveKit** — An open-source WebRTC platform marketed as "The platform for voice, video, and physical AI agents." LiveKit ships an SFU media server, Agents framework for production realtime A... - **Daily** — A WebRTC video API provider offering Prebuilt embeddable video rooms, a Client SDK for custom apps, and Realtime Transport for AI Agents — the underlying infrastructure for Pipe... - **Agora.io** — A realtime engagement platform offering Video Calling, Voice Calling, Signaling, Chat, and a Conversational AI Engine, framed as building "cutting-edge, voice-enabled applicatio... - **Twilio Video / Live** — Twilio's realtime video and live streaming products. Twilio Video provides WebRTC-based group rooms and peer rooms; Twilio Live (in select markets) layers low-latency interactiv... - **Vonage Video API** — A WebRTC video API (formerly TokBox / OpenTok) for embedding live video, audio, and screen sharing into web and mobile apps. Provides session/token-based access control, multipa... - **Amazon Interactive Video Service (IVS)** — AWS's low-latency interactive video service. IVS Real-Time Streaming offers WebRTC-based stages for multi-host interactivity; IVS Low-Latency Streaming offers HLS-based one-to-m... - **Cloudflare Realtime** — Cloudflare's realtime media stack — RealtimeKit (SDKs and APIs for live video/voice), the Realtime SFU ("a powerful media server that efficiently routes video and audio"), and a... - **Socket.IO** — A widely deployed open-source realtime engine for Node.js (with clients across JavaScript, Java, Swift, Kotlin, .NET, Python) that layers reconnection, rooms, namespaces, and bi... - **Phoenix Channels** — The realtime layer of the Elixir Phoenix Framework — soft-realtime channels, presence, and pub/sub built on the BEAM VM. Channels carry WebSocket (or long-poll fallback) topics ... - **Centrifugo** — An open-source language-agnostic realtime messaging server providing WebSocket, SSE, HTTP streaming, and WebTransport transports with channel-based pub/sub, presence, history, a... - **OneSignal** — A multichannel customer messaging platform with Push (mobile + web), Email, SMS & RCS, and In-App Messages — framed as letting teams "set up and send mobile and web push notific... - **Firebase Cloud Messaging (FCM)** — Google's cross-platform push notification and message delivery service for Android, iOS, and web. FCM uses HTTP v1 API for server-to-FCM message submission and a long-lived conn... - **Apple Push Notification Service (APNs)** — Apple's push notification system for iOS, iPadOS, macOS, tvOS, watchOS, and visionOS. APNs uses an HTTP/2-based provider API with token-based or certificate-based authentication... - **Web Push API** — An IETF-standardized push system for the web, comprising the W3C Push API (browser-side subscription), the IETF Web Push Protocol (RFC 8030, server-to-push-service delivery), an... - **Pushwoosh** — A customer engagement platform offering push notifications (mobile + web), in-app messaging, email, and SMS with segmentation, journeys, and a Customer Journey Builder. Uses nat... ## Security (1) - **Realtime Domain Security** — TLSv1.3 · HSTS · DNSSEC · DMARC ## Tags Real-Time, WebSocket, WebRTC, Server-Sent Events, MQTT, Push Notifications, Pub-Sub, Presence, Signaling, Topic --- Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/realtime/). Scores are computed from the provider's own public artifacts under a published rubric.