Location: Berlin, Germany · English (fluent), German (professional)
Email: maya.okonkwo@example.com
Phone: +49 30 1234567
GitHub: github.com/example
LinkedIn: linkedin.com/in/example
Senior Backend Engineer with 8 years building payment and ledger systems. Recent work centres on event-driven services (Kafka, Postgres, Go) and the operational side of running them — idempotency, reconciliation, and the on-call that follows. Looking for a role where correctness under load matters more than shipping speed.
The original ledger stored balances as a mutable column, so a failed payout could leave an account short and nobody could reconstruct why. Rebuilt it as an append-only double-entry ledger in Go and Postgres, with every movement written as balanced entries and balances derived from them. Backfilled 14 months of history and ran both systems side by side for 6 weeks until they agreed to the cent. Reconciliation breaks dropped from ~30 a week to under 2.
Retries from client SDKs were creating duplicate charges under network partitions. Introduced idempotency keys with a Redis-backed claim and a Postgres unique constraint as the final arbiter, so a duplicate request returns the original result rather than a second charge. Handles 1.2M requests/day with duplicate charges down to zero over the following year.
Senior Backend Engineer | Mar 2021 - Present
- Own the ledger and payment intake services: Go, Postgres, Kafka, deployed on Kubernetes.
- Cut p99 settlement latency from 4.2s to 700ms by removing a synchronous fan-out and batching writes.
- Set up consumer-lag alerting and runbooks after an incident where a stalled consumer went unnoticed for 6 hours.
- Review designs across three teams and mentor two engineers.
Backend Engineer | Aug 2018 - Feb 2021
- Built REST and gRPC services in Python and Go for a logistics platform serving 400+ merchants.
- Migrated a shared database into per-service schemas, allowing teams to deploy independently.
- Introduced contract tests between services, cutting integration failures caught in staging by roughly half.
Junior Developer | Jul 2016 - Jul 2018
- Built internal tools in Django and maintained the customer-facing API.
- Took the on-call rotation and wrote the first incident postmortems the team had.
- Languages: Go, Python, SQL, some Rust.
- Storage: PostgreSQL, Redis, Kafka, S3.
- Patterns: Event-driven architecture, idempotency, double-entry accounting, CQRS.
- Infrastructure: Docker, Kubernetes, Terraform, GitHub Actions.
- Observability: Prometheus, Grafana, structured logging, on-call and incident response.
- Unit, integration and contract testing; property-based tests for ledger invariants.
BSc Computer Science | 2013 - 2016