What Is a Chat API?

A Chat API is a set of protocols, endpoints, and SDKs that let you add real-time messaging to your application without building the messaging infrastructure yourself. Here is what a Chat API does, how it works, and what to look for.

Definition

A Chat API provides real-time messaging as a managed service. You integrate it into your app (via SDK or direct WebSocket/HTTP), and users can send and receive messages in real time without you building the message server, scaling layer, persistence database, pub/sub, or reconnection logic. Examples: openbnet Chat, Twilio Conversations, Sendbird, Stream.

What a Chat API handles for you

• WebSocket connection management (connect, reconnect, heartbeat)
• Message delivery (real-time push to connected clients)
• Message persistence (history, replay on reconnect)
• Pub/sub fan-out (one message to many subscribers)
• Cross-server sync (Redis adapter or similar)
• Presence (online/offline status)
• Typing indicators and read receipts
• File/media attachments
• Content moderation (image/text filtering)
• Scaling to thousands of concurrent connections

How a Chat API works

The core pattern: each client opens a WebSocket connection to the chat server. When a user sends a message, the server publishes it to a channel (room). All clients subscribed to that channel receive the message in real time. The server also persists the message to a database so new joiners can load history. For scaling, multiple server nodes sync state via Redis Pub/Sub so a message published on server A reaches subscribers on server B.

// Connect to a chat room via openbnet
const ws = new WebSocket(
  `wss://openbnet.cloud/sv/ws/chat/${room}/${userId}/${username}`
);

// Last 50 messages auto-load on connect
ws.onmessage = (e) => {
  const data = JSON.parse(e.data);
  if (data.type === 'history') {
    data.messages.forEach(renderMessage);
  } else {
    renderMessage(data);
  }
};

// Send a message
ws.send(JSON.stringify({ message: "Hello!", datatype: "text" }));

What to look for in a Chat API

• Latency: target <100ms end-to-end for a natural feel
• Persistence: message history loaded on reconnect, not lost
• Scaling: can it handle your peak concurrent connections?
• File uploads: image, video, audio, document support
• Moderation: AI text/image filtering in the pipeline
• Cross-server sync: does it scale beyond one Node process?
• SDKs: native support for your platforms (Web, iOS, Android, Flutter)
• Pricing: per-message vs flat-rate — which fits your usage?

openbnet Chat API

openbnet Chat runs over WebSocket with Redis Pub/Sub cross-server sync, handling 100K+ concurrent connections per server and 50K messages per second with <100ms end-to-end latency. It includes persistent history (last 50 messages auto-loaded on connect), multi-datatype file uploads (text, image, video, audio, document), and integrated AI content moderation. Start free — no credit card.

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