Kafka vs Azure Event Hubs

Azure Event Hubs is Microsoft's managed streaming platform, often described as "Kafka-as-a-Service on Azure." It offers a Kafka-compatible endpoint, meaning existing Kafka producers and consumers can connect to Event Hubs with just a connection string change.

Architecture Comparison

Kafka uses topics, partitions, and consumer groups. Event Hubs mirrors this with event hubs (topics), partitions, and consumer groups. The Kafka surface endpoint translates Kafka protocol calls to Event Hubs operations.

Event Hubs uses throughput units (TUs) as its scaling unit. Each TU provides 1 MB/s ingress and 2 MB/s egress. Auto-inflate can scale up to 40 TUs automatically. Premium and Dedicated tiers offer more capacity.

Kafka Compatibility Depth

Event Hubs supports most Kafka producer and consumer APIs (Kafka 1.0+). Basic produce/consume, consumer groups, and offset management work. However, Kafka Streams, ksqlDB, and some Connect connectors may not work correctly because they rely on Kafka internals not exposed by Event Hubs.

Capture and Long-Term Storage

Event Hubs Capture automatically writes incoming events to Azure Blob Storage or Data Lake in Avro format. This is simpler than setting up Kafka Connect S3 sink connectors. For long-term event storage and data lake architectures, Capture is a powerful differentiator.

Cost Considerations

Event Hubs pricing is based on throughput units, ingress charges, and retention days. For moderate workloads on Azure, it is cost-competitive. For very high throughput, self-managed Kafka may be cheaper but requires operational investment.

For Azure-native teams, Event Hubs is the natural choice. For multi-cloud portability or deep Kafka ecosystem needs, self-managed or Confluent-managed Kafka is better. See our system design guide and pricing comparison for details.