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.

(ref:hirist.tech)

Genzeon - Senior Software Development Engineer - .Net/AWS