AWS Glue Schema Registry vs Karapace

AWS Glue Schema Registry is a free cloud service for centrally discovering, controlling, and evolving schemas used by streaming applications. It supplies serializers and deserializers so producers and consumers can share schema definitions during data exchange. Supported formats are Avro v1.11.4, JSON Schema Draft-04, Draft-06, and Draft-07, plus Protocol Buffers proto2 and proto3; Protobuf extensions and groups are not supported. Eight compatibility modes are available: NONE, DISABLED, BACKWARD, BACKWARD_ALL, FORWARD, FORWARD_ALL, FULL, and FULL_ALL. Features include automatic registration, metadata-based schema sourcing, IAM compatibility, and optional ZLIB compression. Documented integrations cover Apache Kafka, Amazon MSK, Kinesis Data Streams, Amazon Managed Service for Apache Flink, AWS Lambda, AWS Glue streaming, and Apache Kafka Streams. Client API traffic uses TLS over HTTPS, and schemas are encrypted at rest with an AWS KMS service-managed key. Registry ARNs organize permissions for schema operations.

Karapace is Aiven’s open-source Schema Registry and REST Proxy for Aiven for Apache Kafka. The registry stores and versions schemas, then checks compatibility before a changed schema is published. It accepts Avro, Protobuf, and JSON Schema, with references supported for Avro and Protobuf. Compatibility modes include NONE, BACKWARD, BACKWARD_TRANSITIVE, FORWARD, FORWARD_TRANSITIVE, FULL, and FULL_TRANSITIVE. The REST Proxy exposes HTTP endpoints for producing and consuming Kafka events, so scripts, curl, and HTTP services can work with events. OAuth 2.0/OIDC authentication is available for both components. Registry ACLs and OIDC role-based rules can limit operations, including by HTTP method. Example identity providers include Auth0, Okta, Google Identity Platform, and Azure. Deployment documentation covers Docker and installation from source with pip; the API is stated to support Schema Registry 6.1.1 operations. Karapace is available in Aiven’s Kafka free tier for learning, prototyping, and evaluation. The Free plan costs nothing, while Developer costs $35 a month.