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Realtime Chat Service

WebSocket chat backend handling 50k concurrent connections per node, with Redis pub/sub.

Year 2023
Role Backend engineer
Type SaaS infrastructure
Status Live

About this project.

Existing chat service was a single-process Socket.IO server falling over above 8k concurrent users. Goal: horizontal scaling without rewriting client code.

Sharded the connection layer behind an Nginx upstream that uses sticky sessions, swapped in a Redis adapter for cross-node broadcasts, added presence tracking via Redis sets with TTLs. Single node now sustains 50k concurrent.

Screenshots

Feature set

Sharing and access

  • Signed, expiring download links
  • Embedded admin panel
  • Public landing pages

Operations

  • Single binary Docker image
  • Health checks and JSON logs
  • No external dependencies

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