Back-End Developer

Horizon Labs; United States; On-site; USD 100,000 - 150,000; Full time

Job summary

Horizon Labs is seeking an experienced backend engineer to design and operate reliable APIs and services. You will own data models, performance, security, and cost while shipping features quickly and keeping systems healthy.

Location is the United States or Türkiye, with two-week sprints and trunk-based development. You will collaborate across teams to ensure reliable releases and measurable outcomes.

Qualifications

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

Responsibilities

• Design and implement REST-first services with GraphQL/gRPC when justified.
• Model data in PostgreSQL/MySQL; write efficient queries and indexes.
• Build async jobs and event flows using queues/streams.
• Integrate third-party APIs with signature verification and replay protection.
• Enforce security: least-privilege IAM, secret handling, input sanitization.
• Optimize performance and cost: caching, batching, N+1 reductions.
• Write tests and keep CI green; small, reversible PRs.
• Instrument code with logs/metrics/traces and perform RCAs.
• Document runbooks, data contracts, and decisions for accessibility.

Skills

Node.js

TypeScript

C# /.NET

Go

Python

SQL

NoSQL

CI/CD

Observability

HTTP / Concurrency

Communication

Tools

Prisma

TypeORM

EF Core

Docker

GitHub Actions

GitLab CI

OpenTelemetry

Prometheus

Grafana

Sentry

Redis

MongoDB

Job description

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 HTTP, 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.