Senior Backend Developer

We are looking for a Senior Backend Developer to design and develop .NET services, ensuring reliability, security, and performance.

### Responsibilities * Design and develop .NET services: application business logic, payment and orchestration flows * Ensure reliability: idempotency, retries, deduplication, outbox/Saga, failure handling * Integrate external APIs: correct handling of headers/cookies, formats (multipart/x-www-form-urlencoded, JSON), compliance with specifications * Design databases (PostgreSQL): schemas, indexes, migrations, query and lock optimization * Work on performance and scalability: profiling, reducing p95/p99, caching, throttling * Ensure security: secret storage/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, schema design, 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

### Will be a plus * 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