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Aiven is seeking a Fullstack Software Engineer to join the Kafka Ecosystem team. You'll build features end-to-end across the full stack: production Python in the platform that orchestrates managed Apache Kafka services across clouds, contributions to Karapace (an open-source Schema Registry and Kafka REST Proxy), and React interfaces that deliver those features to users.
Key responsibilities include extending and maintaining Karapace with schema compatibility logic, REST Proxy features, and Confluent API compatibility; keeping the connector ecosystem healthy through upgrades, releases, and security fixes for connectors like Debezium, JDBC, S3, BigQuery, and OpenSearch sinks; participating in design and code reviews while writing well-tested code; shipping code reliably through CI/CD pipelines (Buildkite, GitHub Actions); investigating and resolving production issues across the stack from async Python application code to Linux system behavior; contributing to technical planning within a small team; and owning features end-to-end from API design through backend implementation to React/TypeScript UI delivery.
Required qualifications include strong Python skills with async/await patterns, event loop semantics, and production-grade code with type annotations and tests; full-stack ability to contribute confidently to React/TypeScript codebases; distributed systems fundamentals including consistency, replication, and failure modes; familiarity with schema formats and evolution (Avro, JSON Schema, Protobuf); Linux fundamentals including process management and OS-level debugging; fluency with AI-assisted development tools (Claude Code or similar) as part of daily workflow; and fluent English written and verbal.
Nice-to-have skills include hands-on Apache Kafka experience, Kafka Connect and connector development, prior open-source contributions, experience with public clouds and cloud-managed Kafka, working Java knowledge, schema registry experience, and observability tooling expertise.
The role offers open-source work that ships publicly with your name on commits, deep technical problems spanning multi-format schema compatibility and connector orchestration, end-to-end ownership from design through shipping, and direct impact in a team large enough for ambitious problems but small enough that your technical judgment shapes what gets built. The position is based in Helsinki with a hybrid schedule of 3 days per week in the office.
