C# / .NET Developer -- API Identity authentication and authorization services

Job Description

C# / .NET Developer - API Identity authentication and authorization services (Mid-Level)

About the Role

We are looking for a mid-level C# / .NET developer to build and maintain high-performance API services that power our trading platform. You will work on various .NET API services other across the platform, specifically around our identity authorization and authentication API. This is a backend-focused role. You will work with Redis and relational databases to deliver scalable and reliable APIs in a production trading environment. Strong .NET fundamentals and comfort with distributed systems are important.

What You'll Work On

• Cross-service features - API services using SQL (PostgreSQL or SQL Server) and Redis, across the broader platform

• Redis-backed data access - Reading and serving cached data snapshots with low latency; session and user-state management across data servers

• API platform patterns - Building on our internal REST server framework: dual-port public/private hosting, Swagger documentation, compression, CORS, and standardized error handling

Responsibilities

• Design, implement, and maintain REST API endpoints in C# / ASP.NET Core (.NET 8+)

• Experience with authorization and authentication best practices including OAuth 2.0, API keys, JWT tokens, MFA, key rotation, etc.

• Integrate with Redis for caching, snapshots, and pub/sub patterns using StackExchange.Redis and related libraries

• Write and optimize SQL queries and stored procedures against PostgreSQL or SQL Server as needed

• Add Swagger/OpenAPI documentation and follow established API conventions

• Tune performance for high-throughput, low-latency scenarios (thread pool configuration, connection pooling, async patterns)

• Participate in code reviews, troubleshooting production issues, and iterative feature delivery

Required Qualifications

• 3-5 years of professional experience with C# and .NET (ASP.NET Core)

• Solid understanding of REST API design, HTTP semantics, and API versioning practices

• Comfort with async/await, dependency injection, and standard .NET service patterns

• Experience with Redis - caching, key design, connection management, and basic pub/sub

• Experience with relational databases - writing queries, understanding indexes, and working with PostgreSQL or SQL Server

• Familiarity with Git, CI/CD pipelines, and deploying services to production

Nice to Have

• Experience with Polly or similar resilience libraries (retries, circuit breakers)

• Experience with performance logging, observability, and production debugging under load