Senior Backend Developer (.NET)

About the Role The company is a B2C gaming startup building a high-performance sweepstakes platform already serving real users. The system handles real-time transactions at scale in a regulated space — reliability, speed, and security are paramount. The company operates lean, with backend engineers owning their services from architecture to production. Engineers here don't just implement — they design, decide, and ship. The company is looking for a Senior Backend Developer with 5+ years of experience who wants real ownership over systems that matter. This isn't a ticket-taking role — you'll be driving system design, making tech stack decisions, and shaping the architecture of a live, real-money gaming platform. You'll design and build backend services using . NET 10, own features end-to-end from architecture through production, and work directly with product, business, and compliance stakeholders. You'll be expected to identify the right tool for the job — whether that's choosing between Postgres and MongoDB for a given flow, deciding when WebSockets beat HTTP, or deciding what doesn't need to be built at all. Responsibilities Lead system design and architecture for backend services using . NET 10 Choose the right tech stack for each problem and justify those decisions Architect scalable, secure, and high-performance APIs and real-time systems Design data models and flows across PostgreSQL and MongoDB based on access patterns, consistency needs, and scale Build real-time gameplay and transaction features using WebSockets and event-driven patterns Apply backend best practices — clean architecture, SOLID, KISS, testing, logging, and monitoring — pragmatically, not dogmatically Own features end-to-end — from architecture and implementation through deployment, monitoring, and iteration in production Manage CI/CD pipelines and AWS infrastructure for the services you own Collaborate directly with product, business, and compliance stakeholders to shape what gets built Use AI coding agents (Claude Code, Codex, Cursor, etc.) to raise both velocity and quality Requirements 8+ years of backend development experience, with strong fluency in modern . NET (C# / . NET 6+) Hands-on experience working in startup environments, ideally in small, senior engineering teams with significant individual ownership Proven experience building and operating high-load, high-traffic production systems Demonstrated experience owning system design and architecture decisions on production systems Strong experience with both PostgreSQL and MongoDB — including schema design, indexing, and choosing between them based on workload Experience building real-time systems with WebSockets Track record of taking complex features end-to-end: design, implementation, deployment, and production ownership Ability to choose and justify a tech stack rather than just consume one Strong analytical and problem-solving skills, with a bias toward simple, correct solutions Comfortable with full ownership in a lean startup environment — no hand-holding, no hiding Experience with or strong willingness to adopt AI coding tools Independent, proactive, opinionated, and solution-oriented Nice to Have Experience in gaming, sweepstakes, fintech, or other high-scale B2C platforms Experience with AWS (ECS, RDS, etc.) Experience with message queues and event-driven / asynchronous architectures Experience designing for regulated environments (compliance, auditability, PII handling) About the Company The company is a B2C gaming startup building a high-performance sweepstakes platform already serving real users. The system handles real-time transactions at scale in a regulated space. They operate lean, with a small, senior team and minimal bureaucracy, allowing decisions to be made quickly. The environment is fast-paced and focuses on meaningful ownership over core systems.