Realtime
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).
More than an index entry, but the surface is still mostly links rather than artifacts — the cohort most likely to move a full band from modest, well-targeted work.
API Evangelist profiles Realtime the way a machine reads it — 43 machine-readable artifacts across 26 APIs, pulled from the provider's own public surface and indexed so a developer, an analyst, or an AI agent can evaluate it against every other provider on the network.
Every provider in the network is reduced to the same set of machine-readable artifacts — OpenAPI contracts, event specifications, GraphQL schemas, runnable collections, pricing and rate-limit signals, security posture, OAuth scopes, and the agent surfaces (MCP servers and skills) that let software drive the API on its own. We profile them because the interface is the part of a company you can actually inspect: it is a truer signal of what a provider does than any marketing page. From those artifacts we compute the Kin Score — Realtime scores 26.8/100 (emerging), with a separate agent-readiness read of 7/100 (human only). The full breakdown is below, followed by every artifact we hold — each card links through to its machine-readable definition on apis.io.
Kin Score
This is the API Evangelist rating — a single, repeatable read computed from the artifacts on this page. Green fill is points earned; the red track is points possible, so every bar shows earned-versus-possible at a glance.
How we profile Realtime
Each block below is one kind of artifact we hold for Realtime. For each we say what it is and why it earns a place in the profile, then list every one we've indexed — capped at two rows, scroll within the panel for the rest.
APIs 26
Each API is captured as its own OpenAPI definition — every operation, parameter, and response. This is the single most useful machine-readable description of what an API does, and it's what lets us score, lint, mock, and generate against it without asking the provider for anything.
Individual APIs this provider publishes, each with its own machine-readable definition.
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...
Scroll within the panel for all 26 ·
GraphQL 1
Where a provider ships GraphQL, the schema is the contract. We profile it alongside the REST surface so the whole interface is legible in one place.
GraphQL schemas published by this provider.
Realtime GraphQL API
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...
GRAPHQLSemantic Vocabularies 1
JSON-LD contexts give the data shared meaning across APIs. We profile them because semantics are what let a machine reconcile 'customer' here with 'customer' somewhere else.
JSON-LD contexts and semantic vocabularies used across these APIs.
Realtime Context
JSON-LDSpectral Rules 1
Governance rulesets we run against this provider's specs — the automated checks behind parts of the score. Profiling them makes the quality bar explicit and re-runnable, not a matter of opinion.
Realtime API Rules
SPECTRALJSON Schema 4
Standalone JSON Schema definitions describe the data models behind the API. We profile them so the shapes are validatable on their own — useful long after a single request is forgotten.
Standalone JSON Schema definitions for this provider's data models.
Realtime Channel
JSON SCHEMARealtime Message Envelope
JSON SCHEMARealtime Presence
JSON SCHEMARealtime Subscription
JSON SCHEMAExamples 9
Real request and response payloads are what turn a spec from abstract into obvious — and they're one of the twelve things an agent needs to call an API correctly on the first try.
Example request and response payloads for these APIs.
Scroll within the panel for all 9 ·
Security Posture 1
Authentication, domain security, vulnerability disclosure, and trust-center signals — the evidence that a provider takes security seriously enough to document it. We profile it because you can't govern what you can't see.
Authentication, domain security, vulnerability disclosure, and trust-center signals.
Resources
Every other property we hold for Realtime — documentation, portals, status pages, policies, and corporate surface — grouped by the job it does, following the integrator's arc from getting started to running in production.
Get Started 1
Portal, sign-up, and the first successful call
Documentation 4
Reference material describing how the API behaves
Design & Contract 2
Pagination, idempotency, versioning, errors, and events
Build 2
SDKs, sample code, and the tooling you integrate with
Access & Security 1
Authentication, authorization, and security posture
← All providers · Data indexed from github.com/api-evangelist/realtime · machine-readable index on apis.io