Karapace vs oasdiff

Karapace is a free, open-source implementation of the Kafka Schema Registry and Kafka REST Proxy. Its registry stores Avro, JSON Schema, and Protobuf schemas, keeps version histories, and checks compatibility between versions. The REST Proxy exposes HTTP APIs for producing and consuming Kafka events and handling administrative operations. Karapace implements the Confluent Schema Registry API and REST Proxy API versions 1 and 2, with version 2 as the default. A leader-and-replica design provides high availability and load balancing. Monitoring includes Prometheus-native metrics and OpenTelemetry traces and metrics, with optional Sentry reporting. Schema Registry authentication supports HTTP basic authentication and OAuth2/OIDC bearer-token validation; the REST Proxy forwards OAuth2 tokens instead of validating them. Karapace is self-hosted, requires Python 3.12 or newer, and installs from Docker images or source. Default Docker ports are 8081 for the Schema Registry and 8082 for the REST Proxy. It is offered at free.

oasdiff compares OpenAPI specifications, produces changelogs, and identifies breaking changes before release. It supports OpenAPI 3.0, 3.1, and 3.2, and detects 755 distinct breaking and non-breaking API changes. The CLI is available through Homebrew, a shell installer, Docker, and pre-built Linux, macOS, and Windows binaries. Output formats include text, JSON, YAML, HTML, Markdown, and GitHub Actions annotations. Its GitHub Action compares pull-request and base-branch specifications, adding inline annotations for breaking changes. A browser diff tool compares OpenAPI or Swagger specifications without installation or sign-up. Specs and changelogs are encrypted client-side before upload, and servers retain ciphertext they cannot read. The open-source engine, CLI, and GitHub Action use the Apache 2.0 license. A free plan includes CLI diffing, changelogs, GitHub Action annotations, side-by-side review, and encrypted spec storage. Pro costs $100/month and adds approval workflow, audit trail, merge gate, and up to five reviewers across five repositories. Free review links expire after seven days; Enterprise can load specs from GitHub without uploading or storing them.