Real-time & Messagingby SoftwareCrafting

Service Overview

We build real time features that stay correct when connections drop, which is the part that separates a demo from a product. Chat, live dashboards, collaborative editing, presence, and notifications all look straightforward until you handle reconnection, message ordering, missed messages during a disconnect, and the same user on three devices. We choose the transport deliberately rather than reaching for WebSockets by default: server sent events where the server streams and the client mostly does normal requests, WebSockets where genuine bidirectional low latency communication is needed, and polling where simplicity and infrastructure compatibility matter more than efficiency. On the server side we design for horizontal scale from the start, since a single process holding connection state is a scaling ceiling you hit abruptly. That means a pub/sub backbone, sticky routing or a stateless design, presence tracking that survives a process restart, and message persistence so a client that was offline can catch up rather than silently missing events.

Technologies we use

Key Features

• Kafka event streaming pipelines
• RabbitMQ message queue setup
• BullMQ background job processing
• WebSocket real-time push with Socket.io
• Server-Sent Events (SSE) for live feeds
• Firebase Realtime Database / Firestore sync
• Dead-letter queue & retry strategies
• Horizontal scaling of consumers
• Transport chosen deliberately across WebSockets, server sent events, and polling
• Reconnection with backoff and catch up of messages missed while offline
• Message ordering and deduplication guarantees
• Horizontal scaling with a pub/sub backbone rather than in process state
• Presence tracking that survives process restarts and multi device users
• Message persistence and history with pagination
• Optimistic updates with reconciliation against server state
• Load testing at realistic concurrent connection counts