Users expect live data. Stock prices update without refreshing. Chat messages appear instantly. Collaborative documents show changes as teammates type. In 2026, real-time features have moved from impressive to expected. Here is how the technology works and when to use it.
Why Real-Time Matters
User Expectations
Applications like Slack, Google Docs, Figma, and social media feeds have trained users to expect real-time updates. A dashboard that requires manual refresh feels broken. A chat that needs a page reload feels ancient.
Business Applications
Real-time functionality enables:
- Live dashboards: Sales figures, inventory levels, and analytics updating continuously
- Collaborative editing: Multiple users editing the same document simultaneously
- Customer support chat: Instant communication between customers and support agents
- Notifications: Order status updates, system alerts, and activity feeds
- Live inventory: E-commerce showing real-time stock levels
- Auction and bidding: Live price updates in competitive marketplaces
- IoT monitoring: Sensor data displayed in real-time
Technologies for Real-Time Data
Server-Sent Events (SSE)
The simplest real-time technology. The server pushes data to the client over a standard HTTP connection.
How it works:
- Client opens a connection to the server
- Server keeps the connection open
- Server sends data whenever it has updates
- Client receives updates automatically
// Server (Next.js Route Handler)
export async function GET() {
const encoder = new TextEncoder();
const stream = new ReadableStream({
start(controller) {
const interval = setInterval(() => {
const data = JSON.stringify({ price: getStockPrice() });
controller.enqueue(encoder.encode(`data: ${data}\n\n`));
}, 1000);
// Clean up when client disconnects
return () => clearInterval(interval);
},
});
return new Response(stream, {
headers: {
'Content-Type': 'text/event-stream',
'Cache-Control': 'no-cache',
'Connection': 'keep-alive',
},
});
}
// Client
const eventSource = new EventSource('/api/stock-price');
eventSource.onmessage = (event) => {
const data = JSON.parse(event.data);
updatePrice(data.price);
};
Best for: One-way data flow from server to client — live feeds, notifications, dashboards.
Pros: Simple to implement, works over HTTP, automatic reconnection, wide browser support.
Cons: One-directional (server to client only), limited to text data, can be blocked by some proxies.
WebSockets
Full-duplex communication channel between client and server. Both sides can send data at any time.
How it works:
- Client initiates an HTTP request and upgrades to WebSocket protocol
- Persistent bidirectional connection is established
- Both client and server can send messages at any time
- Connection stays open until explicitly closed
Best for: Bidirectional communication — chat, collaborative editing, multiplayer games, interactive features.
Pros: True bidirectional, low latency, supports binary data, works with any data format.
Cons: More complex to implement, requires WebSocket-compatible infrastructure, more resource-intensive.
Long Polling
A fallback technique for environments that do not support SSE or WebSockets:
- Client sends a request to the server
- Server holds the request open until new data is available
- Server responds with the new data
- Client immediately sends a new request
- Repeat
Best for: Environments with strict network restrictions. Generally avoided in 2026 when SSE and WebSockets are available.
Real-Time Platforms
Pusher
Hosted real-time service:
- WebSocket connections managed for you
- Channels for organizing real-time data
- Presence channels for knowing who is online
- Client libraries for every platform
- Free tier: 200K messages/day, 100 connections
Ably
Enterprise real-time messaging:
- Guaranteed message delivery
- Message history and persistence
- Global edge network for low latency
- Advanced features: presence, history, push notifications
- Free tier: 6M messages/month
PartyKit
Modern real-time collaboration platform:
- Built for collaborative applications
- Runs on Cloudflare's edge network
- Server-side logic with WebSocket connections
- Ideal for multiplayer and collaboration features
Supabase Realtime
Real-time database subscriptions:
- Subscribe to database changes via WebSocket
- PostgreSQL LISTEN/NOTIFY under the hood
- Row-level security applies to real-time subscriptions
- Integrated with Supabase's database and auth
Convex
Real-time backend:
- Reactive queries that update automatically when data changes
- No manual subscription management
- Built-in conflict resolution
- Type-safe from database to UI
Implementation Patterns
Optimistic Updates
Show changes immediately before server confirmation:
function addComment(text: string) {
// Immediately show the comment in the UI
setComments(prev => [...prev, { text, status: 'sending' }]);
// Send to server
const result = await api.postComment(text);
if (result.success) {
setComments(prev => prev.map(c =>
c.text === text ? { ...c, status: 'sent', id: result.id } : c
));
} else {
// Remove the optimistic comment
setComments(prev => prev.filter(c => c.text !== text));
showError('Failed to post comment');
}
}
This makes the interface feel instant even though server confirmation takes 100-500ms.
Conflict Resolution
When multiple users edit the same data:
- Last write wins: Simplest approach. The most recent change overwrites all others. Acceptable for simple use cases
- Operational Transformation (OT): The algorithm Google Docs uses. Transforms concurrent operations to maintain consistency
- CRDTs (Conflict-free Replicated Data Types): Mathematical structures that merge concurrent changes without conflicts. Used by Figma and other modern collaborative tools
Connection Management
Real-time connections require careful management:
- Reconnection: Automatically reconnect when connections drop (mobile switching networks, temporary outages)
- Backoff: Implement exponential backoff on reconnection attempts to avoid overwhelming the server
- State reconciliation: When reconnecting, sync any changes that occurred during disconnection
- Heartbeats: Periodic pings to detect dead connections
When to Go Real-Time
Worth the Complexity
- Chat and messaging (core feature is real-time communication)
- Collaborative editing (multiple users need to see each other's changes)
- Live dashboards with frequently changing data
- Notification systems where timeliness matters
- Auction/bidding platforms (competitive timing)
Not Worth the Complexity
- Blog or marketing content (changes infrequently)
- E-commerce product pages (refresh on checkout is fine)
- Forms and data entry (user submits, waits for response)
- Reports and analytics (periodic refresh is sufficient)
The Middle Ground
Many applications benefit from "near real-time" rather than truly real-time:
- Polling every 10-30 seconds for dashboard updates
- SSE for important notifications only
- Real-time for active collaboration, polling for ambient data
This reduces infrastructure complexity while providing a responsive experience.
Performance and Scaling
Connection Limits
Each WebSocket connection consumes server resources. A server typically supports 10,000-50,000 concurrent WebSocket connections. For larger scale:
- Use a managed service (Pusher, Ably) that handles scaling
- Implement connection limits per user
- Use SSE instead of WebSockets where one-directional suffices (lower resource usage)
- Close idle connections after a timeout
Message Size
Keep real-time messages small:
- Send only changed data, not full objects
- Compress messages for binary WebSocket connections
- Batch small frequent updates into periodic larger updates (every 100-500ms)
Our Real-Time Expertise
At RCB Software, we build real-time features that enhance user experience without unnecessary complexity. From live chat and notifications to collaborative dashboards, we choose the right technology for your specific needs. Contact us to discuss real-time features for your application.