Back-End Developer

Design and operate reliable APIs and services. Own data models, performance, security, and cost. Ship features fast, keep systems healthy, and measure outcomes.

Location: United States or Türkiye only. We do not hire outside these countries.

What you'll deliver in your first 90 days

• Ship 3+ backend features across one or two projects with on-time delivery ≥85%.
• API performance baselines: p95 ≤300ms on critical endpoints; error rate trending down week over week.
• Observability live: structured logs, metrics, traces, dashboards, and actionable alerts.
• Test coverage on critical paths ≥80% with unit, integration, and API tests running in CI.
• Safe data changes: migration + rollback playbook, verified backups, and retention policies.
• Security baseline: input validation, authz/authn, rate limiting, secret management, and audit logs.
• CI/CD ready: build-to-prod lead time ≤24 hours; one-click rollback; tagged releases.
• Two ADRs documenting significant design choices and trade-offs.

Responsibilities

• Design and implement REST-first services; use GraphQL or gRPC when justified. Handle versioning, idempotency, pagination, and consistency.
• Model data in PostgreSQL/MySQL; write efficient queries, indexes, and transactions. Use Redis/Mongo where it fits.
• Build async jobs and event flows with queues/streams (SQS, BullMQ, Kafka, or RabbitMQ). Ensure retries and dead-letter handling.
• Integrate third-party APIs and webhooks with signature verification and replay protection.
• Enforce security practices: least-privilege IAM, secret handling, input sanitization, output encoding, and dependency scanning.
• Optimize performance and cost: caching, batching, eliminating N+1, background processing, and storage tiers.
• Write tests at the right levels; keep CI green and PRs small, reversible, and reviewed.
• Instrument code with logs/metrics/traces; debug using telemetry and RCAs.
• Document runbooks, data contracts, and decisions where others can find and use them.
• Partner with Frontend, QA, and DevOps for smooth releases and environment parity.

Requirements

• 3+ years as a backend engineer at a startup or agency, shipping production systems.
• Strong in one of Node.js (TypeScript/NestJS/Express) or C#/.NET; plus familiarity with Go or Python is a plus.
• SQL fluency (PostgreSQL/MySQL) and practical NoSQL use (Redis/Mongo). ORMs like Prisma, TypeORM, or EF Core.
• CI/CD with GitHub Actions or GitLab CI; Docker-based workflows.
• Observability tooling: OpenTelemetry, Prometheus/Grafana, and Sentry (or equivalents).
• Solid understanding of networking, and concurrency.
• Clear written communication and steady async collaboration.
• Time-zone overlap: minimum 4 hours with Pacific Time or Türkiye time, depending on team.
• Based in the United States or Türkiye.

Nice to have

• Event-driven architectures, outbox/CQRS patterns, and change data capture.
• Elasticsearch/OpenSearch, PostGIS, or analytical warehouses.
• Serverless and edge (AWS Lambda, CloudFront/Cloudflare Workers).
• Compliance exposure (SOC 2, HIPAA) and secure data handling.
• LLM/AI feature integration, vector stores, and prompt/tooling hygiene.
• Domain experience in marketplaces, healthtech, B2B SaaS, or embedded/IoT.

How we work

• Two-week sprints, trunk-based development, frequent releases.
• Definitions of Ready/Done and release checklists on every project.
• Blameless postmortems; written decisions live in the repo or Notion.

Application items

• Resume or LinkedIn.
• Links to two code samples or a small repo (redact secrets) showing API design and data modeling.
• A short note on a reliability or performance improvement you delivered, with before/after metrics.

Horizon Labs builds MVPs, modernizes legacy systems, and integrates complex stacks for startups and SMBs.