An open-source distributed tracing system, the CNCF reference implementation that most teams start with.
Jaeger is an open-source, end-to-end distributed tracing system originally built at Uber and donated to the CNCF. It accepts OpenTelemetry, Jaeger-native, and Zipkin trace formats; stores them in Elasticsearch, Cassandra, or in-memory; and provides a web UI for exploring traces, building service dependency graphs, and analyzing latency. Jaeger is one of the two reference open-source tracing backends (alongside Tempo); commercial tools like Honeycomb, Datadog, and Nova consume the same OTel feed.
Most teams start their tracing journey with Jaeger because it's free, OTel-compatible, and well-documented. Even teams that later migrate to a managed backend often keep Jaeger in non-prod environments. Knowing the Jaeger UI is now a baseline expectation for SRE roles in microservice shops.
See the part of the platform that handles jaeger in production.