Zipkin

Zipkin pioneered distributed tracing — it's the tool Twitter built to understand how requests flow through microservices. Send spans from your services, and Zipkin gives you a visual trace showing exactly where latency lives.

If you're debugging slow requests across microservices, you need distributed tracing, and Zipkin is the battle-tested option. Jaeger (from Uber, now CNCF) is the more modern alternative with better Kubernetes integration and a richer UI. OpenTelemetry is the standard for instrumentation and can export to either. Commercially, Datadog APM, New Relic, and Honeycomb offer tracing with much better UX.

The simplicity is appealing. Zipkin runs as a single Java jar, accepts multiple wire formats, and the dependency graph view is genuinely useful for understanding service topology.

The catch: Zipkin shows its age. The UI feels dated compared to Jaeger or commercial tools. The query capabilities are limited — complex trace analysis requires exporting data elsewhere. Most teams starting fresh in 2026 should look at Jaeger or go straight to OpenTelemetry Collector with a backend that supports trace analytics. Zipkin earned its place in history, but the ecosystem has moved on.