C#/.Net Engineer

Brilliant Infotech Inc.; Hamilton (NJ); Hybrid; USD 130,000 - 180,000; Full time

Job summary

Brilliant Infotech Inc. is seeking an experienced C#/.NET Engineer to lead modernization of a legacy benefits system hosted on AWS. This contract, hybrid in Hamilton, NJ, role focuses on refactoring, service layer and API development, and performance optimization for nightly batch windows.

You will guide architectural decisions, mentor junior developers, and ensure functional equivalence with robust tests and CI/CD integration. Strong PostgreSQL/EF Core expertise is required.

Qualifications

• 12–15 years of professional C#/.NET experience with senior/lead responsibilities.
• Deep expertise in C#, .NET Framework/Core, async programming, and performance tuning.
• Expert EF Core: modeling, Fluent API, migrations, transactions.
• Strong PostgreSQL schema design, indexing, and query tuning.
• REST API design with ASP.NET Core Web API.
• Solid understanding of SOLID, layered architecture, and DI.
• Testing discipline with unit/integration/regression testing.
• Experience reading and safely refactoring large codebases; attention to accuracy in financial calculations.

Responsibilities

• Refactor COBOL-derived C# into idiomatic .NET with proper OO design.
• Build service layers, domain models, and APIs backing the Angular UI.
• Migrate legacy batch logic to maintainable .NET with accurate decimal math.
• Optimize batch performance to meet nightly SLAs.
• Lead data access with EF Core against PostgreSQL and migrations.
• Define coding standards and mentor developers.
• Ensure unit and regression tests; integrate with CI/CD and SonarQube.

Skills

C#/.NET

Async programming

EF Core

PostgreSQL

ASP.NET Core

Unit testing

Dependency Injection

Design patterns

Code refactoring

Git/CI/CD

AWS

Npgsql

SonarQube

CodeBuild/CodePipeline

Tools

AWS

Npgsql

SonarQube

AWS CodeBuild/CodePipeline

Job description

Job Description

We are looking for a C#/.NET Engineer to lead the modernization of a mission‑critical legacy benefits system hosted on AWS Cloud. This position will be Contract and hybrid in Hamilton, NJ.

What You’ll Do

• Refactor machine‑converted, COBOL‑derived C# into idiomatic, maintainable .NET meaningful naming, proper OO/domain design, separation of concerns, dependency injection
• Work in .NET (Core) / .NET (latest version); apply modern C# language features (LINQ, async/await, records, pattern matching, nullable reference types, generics)
• Design and implement service layers, domain models, and APIs (ASP.NET Core Web API) that back the Angular UI
• Refactor legacy batch/procedural logic (converted from COBOL/JCL) into maintainable, testable .NET; handle exact decimal/financial arithmetic (decimal, rounding rules) to preserve benefit‑calculation correctness
• Optimize performance to meet the nightly batch window (profiling, memory management, async I/O, parallelism where safe)
• Entity Framework / Data Layer:
• Own the data‑access architecture using Entity Framework Core against PostgreSQL (Npgsql provider)
• Refactor the auto‑generated/converted data‑access layer into a clean, performant EF Core model
• Design entity models, DbContext configuration, Fluent API mappings, relationships, keys, and indexes reflecting the IDS‑II PostgreSQL schema (168 tables, 4,024+ fields)
• Optimize EF Core queries (eager/lazy/explicit loading, projection, AsNoTracking, compiled queries, batching) to avoid N+1 and meet performance SLAs on high‑volume batch operations
• Manage EF Core migrations, concurrency handling, transactions, and connection resilience
• Map legacy data types and semantics correctly (packed decimals, fixed‑width, EBCDIC‑origin data, condition codes) to PostgreSQL/EF types without behavioral drift
• Contribute to the COBOL‑field PostgreSQL‑column business‑term data dictionary
• Technical Leadership:
• Define and enforce C#/.NET coding standards, architecture patterns, and refactoring guidelines for the engineering team
• Serve as senior technical authority on the converted codebase; make cross‑cutting design decisions
• Mentor mid/junior C# developers; perform code reviews; drive engineering quality
• Partner with the Technical Manager/Architect on target architecture and the refactoring strategy
• Quality, Testing & Delivery:
• Ensure functional equivalence: build unit and regression tests (xUnit/NUnit, Moq) to validate refactored code against the legacy baseline; fix FET‑surfaced defects
• Integrate with CI/CD (AWS CodeBuild/CodePipeline), enforce quality/security gates (SonarQube, static analysis, secure coding/OWASP)
• Collaborate with FAMIS SMEs to preserve business logic (eligibility, benefit calculation, payments, EBT)
• Deliver incrementally within Scrum; document design and decisions

Required

• 12‑15 years of professional C#/.NET software engineering, including senior/lead responsibilities
• Deep expertise in C# and the .NET platform (.NET Framework and .NET Core / .NET 6/8+), including async programming, memory/performance optimization, and modern language features
• Expert‑level Entity Framework / EF Core: entity modeling, Fluent API, migrations, query optimization, transactions, concurrency, provider‑specific behavior
• Strong relational database skills; PostgreSQL strongly preferred (Oracle/SQL Server acceptable) schema design, indexing, query tuning, stored procedures
• ASP.NET Core Web API design (REST) for front‑end integration
• Solid software design: SOLID, design patterns, domain modeling, layered/clean architecture, dependency injection
• Testing discipline: unit/integration/regression testing frameworks; TDD/mocking
• Git, CI/CD, and static code analysis (SonarQube)
• Proven ability to read, reason about, and safely refactor large, unfamiliar codebases
• Exceptional attention to correctness financial/benefit calculation accuracy

Preferred

• Legacy modernization experience COBOL‑to‑C#/Java conversion, mainframe migration, or automated‑transformation tooling
• Understanding of mainframe concepts (COBOL, JCL, batch processing, hierarchical/CODASYL databases like IDS‑II/IMS) to reason about source behavior
• High‑volume batch processing performance tuning
• AWS experience (ECS/EKS, Lambda, RDS for PostgreSQL, S3, CloudWatch, IaC/CloudFormation)
• Experience integrating with enterprise job schedulers (Stonebranch, Control‑M, CA7)
• Government / benefits / healthcare or other regulated, high‑correctness domains
• Npgsql specifics, EF Core performance internals, or ORM migration experience