C#/.NET Engineer

CAI; New Jersey; Hybrid; USD 80,000 - 85,000; Full time

Benefits offered by this job

Medical, dental, and vision insurance

401k retirement plan

Paid time off

Job summary

CAI is looking for a highly skilled C#/.NET Engineer to lead modernization of a mission-critical legacy benefits system hosted on AWS. This full-time, hybrid role is based in Hamilton, NJ.

You will refactor COBOL-derived code to idiomatic .NET, design EF Core data access, implement REST APIs with ASP.NET Core, and collaborate with SMEs to preserve business logic and accuracy in calculations. Strong leadership and testing discipline required.

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+), 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).
• 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.

Responsibilities

• Refactor machine-converted COBOL-derived C# into idiomatic, maintainable .NET with proper OO design.
• Work in .NET Core / .NET latest, using LINQ, async/await, and modern features.
• Design and implement service layers, domain models, and APIs that back the Angular UI.
• Refactor legacy logic into maintainable, testable code; preserve exact decimal arithmetic.
• Optimize performance to meet nightly batch windows; profile and parallelize where safe.
• Own EF Core data layer, migrations, and performance tuning; map to PostgreSQL schema.
• Lead technical decisions, enforce coding standards, and mentor developers.
• Ensure unit/regression tests and CI/CD integration; collaborate with SMEs.

Skills

C#/.NET engineering

Entity Framework Core

ASP.NET Core Web API

SQL/PostgreSQL

Async programming

SOLID / design patterns

Unit / integration testing

CI/CD

Performance optimization

Dependency injection

Domain modeling

Mentoring / leadership

Tools

Npgsql

AWS (ECS/EKS, Lambda, RDS)

Git

Job description

C#/.NET Engineer

Req number: R8573

Employment type: Full time

Worksite flexibility: Hybrid

Who we are

CAI is a global services firm with over 9,000 associates worldwide and a yearly revenue of $1.3 billion+. We have over 40 years of excellence in uniting talent and technology to power the possible for our clients, colleagues, and communities. As a privately held company, we have the freedom and focus to do what is right-whatever it takes. Our tailor-made solutions create lasting results across the public and commercial sectors, and we are trailblazers in bringing neurodiversity to the enterprise.

Job Summary

We are looking for a motivated C#/.NET Engineer ready to take us to the next level! If you have expert-level Entity Framework Core experience and are looking for your next career move.

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 full-time 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

Reasonable accommodation statement

If you require a reasonable accommodation in completing this application, interviewing, completing any pre-employment testing, or otherwise participating in the employment selection process, please direct your inquiries to or .

EEO Statement

It is the policy of Computer Aid, Inc.(CAI) not to discriminate against any employee or applicant for employment because of race, color, religion, sex, sexual orientation, gender identity, national origin, age, marital status, genetic information, disability or because he or she is a protected veteran. It is also the policy of CAI to take affirmative action to employ and to advance in employment, all persons regardless of race, color, religion, sex, sexual orientation, gender identity, national origin, age, marital status, genetic information, disability or protected veteran status, and to base all employment decisions only on valid job requirements. This policy shall apply to all employment actions, including but not limited to recruitment, hiring, upgrading, promotion, transfer, demotion, layoff, recall, termination, rates of pay or other forms of compensation and selection for training, including apprenticeship, at all levels of employment.

Employees and applicants of CAI will not be subject to harassment on the basis of race, color, religion, sex, sexual orientation, gender identity, national origin, age, marital status, genetic information, disability or because he or she is a protected veteran. Additionally, retaliation, including intimidation, threats, or coercion, because an employee or applicant has objected to discrimination, engaged or may engage in filing a complaint, assisted in a review, investigation, or hearing or have otherwise sought to obtain their legal rights under any Federal, State, or local EEO law is prohibited.

$58 - $62 per hour

The pay range for this position is listed above. Exact compensation may vary based on several factors, including location, experience, and education.

Benefit packages include medical, dental, and vision insurance, as well as 401k retirement account access. Employees in this role may also be entitled to paid sick leave and/or other paid time off as provided by applicable law.