C#/.NET Engineer

ABAL Technologies Inc; Village of Hamilton (NY); Hybrid; USD 124,000 - 207,000; Full time

Job summary

ABAL Technologies Inc. in Hamilton, NJ seeks a Senior Lead .NET Engineer to modernize a COBOL-derived benefits system hosted on AWS. You will own refactoring, design EF Core data access against PostgreSQL, implement clean architectures, and ensure functional equivalence to the legacy code.

The role is a long-term contract in a hybrid arrangement, requiring deep C#/.NET expertise, strong database and performance focus, and leadership to mentor developers and set engineering standards.

Qualifications

• 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+).
• Expert-level EF Core: modeling, migrations, queries, transactions, concurrency.
• Strong relational databases; PostgreSQL preferred; design and tuning, indexing.
• ASP.NET Core Web API for RESTful services.
• Solid software design: SOLID, patterns, layered/clean architecture; DI.
• Testing discipline: unit/integration/regression testing; TDD/mocking.
• GIT, CI/CD, and static analysis.
• Ability to reason about large legacy codebases and refactor safely.
• Attention to correctness in financial calculations.

Responsibilities

• Refactor COBOL-derived C# into idiomatic, maintainable .NET with proper OO design.
• Build service layers, domain models, and APIs (ASP.NET Core) for the Angular UI.
• Refactor legacy batch/procedural logic for maintainability and testability.
• Optimize performance to meet nightly batch window; memory management and async I/O.
• Own data-access architecture using EF Core against PostgreSQL; design EF mappings and indexes.
• Manage EF Core migrations, concurrency, transactions, and connection resilience.
• Mentor developers; perform code reviews; enforce coding standards and patterns.
• Ensure functional equivalence with the legacy system; build unit/regression tests.
• Integrate with CI/CD (AWS CodeBuild/CodePipeline); enforce gates and security.
• Collaborate with SMEs to preserve business logic for eligibility and benefits.

Skills

C# / .NET

Async programming

Performance optimization

EF Core / Fluent API

PostgreSQL

ASP.NET Core Web API

Unit testing / TDD

Code reviews / mentoring

Dependency injection

Design patterns / SOLID

Tools

PostgreSQL

AWS (ECS/EKS, RDS)

Npgsql

Git / CI/CD

Job description

• *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

We are modernizing a large, mission-critical Honeywell Bull mainframe benefits system (FAMIS) — converting ~1.5M lines of COBOL and ~160K lines of JCL to C#/.NET, migrating an IDS-II hierarchical database to PostgreSQL, and deploying on AWS. Converted code is delivered by an automated modernization vendor in an "as-is" state. This Lead/Principal role owns the refactoring of that converted code into clean, maintainable, high-performance, production-grade C#/.NET, defines the data-access architecture using Entity Framework Core against PostgreSQL, sets engineering standards for the team, and safeguards functional equivalence to the legacy system. This is a benefits system serving NJ families — correctness, performance within the nightly batch window, and maintainability are paramount.

Job Description

We are looking for a C#/.NETEngineer to lead the modernization of a mission-critical legacy benefits system hosted on AWS Cloud. This position will be Long Term 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 resiliency
• 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

What You'll Need

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

Physical Demands

• Ability to safely and successfully perform the essential job functions consistent with the ADA and other federal, state, and local standards
• Sedentary work that involves sitting or remaining stationary most of the time with occasional need to move around the office to attend meetings, etc.
• Ability to conduct repetitive tasks on a computer, utilizing a mouse, keyboard, and monitor