Genzeon - Senior Software Development Engineer - .Net/AWS

Job Description :

The Dev / Senior Developer is the primary builder for both Lambda services, the shared client library, Kafka producer logic, and backfill tooling.

This role requires strong backend engineering skills with hands-on AWS serverless experience.

Required Skills :

- .NET : 4+ years production experience in the primary Lambda runtime; ability to write clean, testable, well-structured code with proper error handling and logging using AWS Lambda's .NET managed runtime (Amazon Lambda Core).

- AWS Lambda & serverless : Practical experience building and deploying Lambda functions, including timeout management, concurrency configuration (reserved and provisioned), cold-start optimization, and Step Functions for orchestration; familiarity with Lambda deployment via AWS SAM or CDK and monitoring via CloudWatch Logs and Lambda Insights.

- REST API integration : Experience consuming third-party REST APIs with pagination, rate-limit handling, retry/back off strategies, and authentication (API key headers); ability to store and rotate API credentials securely using AWS Secrets Manager or Parameter Store. Familiarity with marketing platform APIs is a plus.

- Apache Kafka : Hands-on experience producing messages to Kafka topics on Amazon MSK, including AVRO serialization, Schema Registry integration, producer configuration (acks, retries, idempotency), and troubleshooting publish failures.

- AVRO & Schema Registry : Ability to define, version, and register AVRO schemas; understanding of schema evolution (backward/forward compatibility) and contract-first design.

- Amazon DynamoDB : Experience designing table schemas (partition/sort keys), managing read/write capacity, implementing TTL policies, and using DynamoDB for cursor/state persistence and configuration storage; familiarity with DynamoDB conditional writes for idempotent operations.

- Data pipeline design : Understanding of batch/incremental ingestion patterns, idempotency strategies (composite keys, deduplication), cursor-based change tracking, and data correctness in distributed systems; experience using SQS as a buffer between pipeline stages for resilience and flow control.

- Testing : Strong unit testing discipline; experience with integration testing using mocks, stubs, or sandbox environments for external APIs and Kafka; familiarity with running integration tests against local AWS service emulators (LocalStack) or AWS sandbox accounts.

Desirable :

- Experience with Snowflake or data warehouse ingestion patterns.

- Familiarity with API v2 (contacts, lists, list changes endpoints).

- Experience with historical backfill tooling (phased execution, rate-limit-aware replay).

- Knowledge of PII handling and data minimization in event-driven architectures, including AWS KMS encryption and CloudWatch log filtering for sensitive fields.