In March 2026, zAccess served 50,000 simultaneous exam candidates during a national professional certification event. This is how we engineered it.
Traditional exam platforms vertically scale a single database server. At 50k concurrent WebSocket connections, this approach collapses. We needed a fundamentally different architecture.
Exam answers are written to an in-memory event log first (Redis Streams), then asynchronously persisted to PostgreSQL. This decouples write throughput from database capacity.
Static assets (question content, media) served from 38 edge PoPs globally. Nigerian candidates hit PoPs in Lagos and Abuja — median latency 14ms for asset loads.
We deliberately killed nodes mid-exam in staging to verify graceful failover. Candidates on a failed node reconnected within 800ms with zero answer loss thanks to client-side buffering.
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