Senior Backend Developer

Responsibilities: Designing and developing .NET services: application business logic, payment and orchestration flows Ensuring reliability: idempotency, retries, deduplication, outbox/Saga, failure handling Integrating external APIs: proper handling of headers/cookies, formats (multipart/x-www-form-urlencoded, JSON), compliance with specifications Database design (PostgreSQL): schemas, indexes, migrations, query and lock optimization Working on performance and scalability: profiling, reducing p95/p99, caching, rate limiting Ensuring security: storing secrets/KMS, access control, secure configuration and deployment

Requirements: 5+ years of experience Deep knowledge of network protocols and web integrations: HTTP/2, CORS, cookies, multipart/x-www-form-urlencoded Cryptography and formats: Ed25519, SHA-256, working with binary protocols and byte prefixes Databases: PostgreSQL, designing schemas, indexes, transactions, migrations (EF Core) Microservices and integrations: gRPC/Protobuf, queues/brokers (RabbitMQ/Kafka), Outbox and idempotency patterns Reliability under load: retries, timeouts, polling, rate limiters, circuit breaker Observability: Prometheus/Grafana, structured logging, tracing (OpenTelemetry) Containerization and CI/CD: Docker, basic deployment and configuration practices Clean code and architecture: SOLID, unit and integration tests, code review, API design

Nice to have: Experience with anti-bot mechanisms (e.g., Cloudflare: headers, sessions) Knowledge of DDD and event-driven approaches, Saga/orchestrators, managing transactional boundaries in distributed systems Experience in payment security and anti-fraud, KMS/Secret-management Experience conducting property-based testing, load and performance tests, benchmarks

Send your resume to @katyacheresh