Full Stack .NET Engineer

Biller Genie; Belfast City District; Hybrid; GBP 65,000 - 90,000; Full time

Benefits offered by this job

Private health insurance

Group life death benefit

Pension with 5% employer match

25 days holiday

10 bank holidays

Job summary

Biller Genie seeks a seasoned Full Stack .NET Engineer to join our AI-enabled fintech team in Belfast. You will own significant features and drive them from concept to deployment, with broad responsibilities across the SDLC.

The role expects hands-on coding, architecture ownership, and collaboration with senior engineers in a fast-paced environment. We value practical experience with AI-assisted development and cloud platforms, plus strong UI skills (HTML/JS/CSS, jQuery).

Qualifications

• Degree in Computer Science or related field, or equivalent commercial experience in .NET.
• Minimum 2 years of hands-on .NET/C# development including ASP.NET MVC.
• Experience with Design Patterns, refactoring, and OO design.
• Experience with Web API and cloud platforms (Azure/AWS/GCP).
• Strong HTML, JavaScript, CSS (including jQuery).
• Familiarity with Git, TFS, SVN.
• Legal right to work in the UK.

Responsibilities

• Design and build future-proof solutions aligned to business needs while considering system impact.
• Collaborate with senior engineers to estimate, plan, track, and manage progress and dependencies.
• Gather requirements and release software in a timely fashion.
• Balance speed and efficiency through adaptive work practices.
• Identify, reproduce, and remediate bug tickets with the support team.
• Develop features using agentic tooling and AI-enabled practices.
• Contribute prompts, skills, and workflow improvements back to the team.
• Perform other duties as required by management.

Skills

C#

Java

OO programming

ASP.NET MVC

Web API

HTML

JavaScript

CSS

jQuery

Azure

AWS

GCP

Git

TFS

SVN

UK work rights

AI tooling

Claude

NET Core

Entity Framework

Bootstrap

Education

BSc/MSc in Computer Science

Tools

Claude Code

CI/CD

Job description

Job Title: Full Stack .NET Engineer
Location: Belfast, Northern Ireland
Work Arrangement: Hybrid In-Office

Position Overview: We are seeking experiencedAI-enabled.NET full-stack engineers who can quickly understand our existing codebase and significantly contribute to the development of complex, innovative solutions in our fast-paced fintech environment. As a key member of ourengineeringteam, you will take ownershipofsignificant features, driving them from conception to deployment. We need a versatile ‘Swiss Army Knife’—a engineer who is comfortable across the entire SDLC, from architectural design and implementation to testing and deployment. Your experience andexpertisewill be vital in delivering high-quality, robust solutions. Join our growing team and make a substantial impact on our platform!

**About Us:** Recently ranked #482on the Inc. 5000 fastest growing companies in the United States, Biller Genie is an award-winning B2B SaaS platform that is entering the Belfast market with ambitious plans to scale our team rapidly, with over 100 hires planned through 2026.

We are an AI-enabled engineering team, and we believe the future is about empowering engineers with the latest tools,building through custom skills, agents, and harnesses, and we are looking for people who embrace AI, are excited about the future, and want to help shape the way we embed AI tooling throughout our developer experience.

Primary Job Responsibilities:

• Design & build future-proof solutions to support growing business needs while thoroughly considering the system impact
• Work closely with our senior engineers to develop solutions from idea to implementation by estimating, planning,trackingand managing progress, risks, and dependencies.
• Gather and refine requirements, and release software ina timelyfashion
• Be adaptive and strike a good balance between speed and efficiency
• Work with our technical support team toidentify, reproduce, and remediate bug tickets
• Build and deliver features through agentic tooling — designing, iterating on, and improving our custom skills, agents, and harnesses as part of the work
• Contribute prompts, skills, and workflow improvements back to the team so our AI-enabled developer experience compounds
• Perform other duties required by Management

Essential Criteria:

• BSc or MSc in Computer Science / related qualification OR commercial experience of developing in C#,Javaor other OO programming languages
• Minimum 2years of hands-on commercial experience programming on the .NET platform using C#, including ASP.NET (MVC)
• Experience with Design Patterns, refactoring, OODesignand related areas
• Practicalhands-onexperience with AIcoding assistantsand agentic engineeringworkflows, and a genuine appetite to work primarily through agents — owning architecture, review, and quality rather than typing every line
• Exposure to building web services using Web API
• An understanding of database design and development
• Hands-on experience with HTML, JavaScript, CSS including jQuery
• Strong attention to detail and work ethic
• Strong analytical and problem-solving skills
• Excellent communication (both written and verbal) and interpersonal skills
• Experience of cloud technologies such as Azure/AWS/GCP
• Previousexperience working with source control tools (TFS, SVN, or GIT)
• Legal right to work in the UK

Desirable Criteria:

• Experience with Azure Functions and Queues
• Experience building custom agent skills, harnesses, MCP servers, or prompt libraries
• Experience defining evals, guardrails, or review practices for AI-generated code
• Experience in testing methodologies
• Experience of LEAN software development practices
• Knowledge of CI/CD systems and implementation practicesHands-on experience with front-end frameworks such as Bootstrap
• Knowledge on .NET Core and Entity framework Code First migrations
• Proficient with Claude or Claude Code
• Experience in Financial services industry
  What We Offer :
• Private health insurance
• Group life death benefit
• Auto-enrollment pension with employer contributions matched to 5%
• 25 days holiday per year
• 10 statutory/bank holidays per year
• Opportunities for professional growth and development
• A collaborative and innovative work environment
  Our Mission: To provide an automated A/R platform that seamlessly integrates existing business processes for the SMB market.

Our Core Values:
Get Shit Done Right -We work hard and ensure tasks are completed correctly and on time, every time.
Own it- We are subject matter experts who know what we know, and we are confident enough to speak up when we see something wrong.
_Catch Up -_We are high performers and love a fast-paced environment.
_Believe in the Genie -_We are passionate about where we are going as a team, and we show we care.
_Class Shines -_We are articulate professionals who carry ourselves well and speak with purpose.

How We Work: Our engineers work with agents and harnesses as a default, not an experiment. Our interview process includesa practicalexercise using AI tooling. If that sounds like the way you want to build, you will thrive here; if you would rather write every line by hand, this islikely notthe right fit.

Please note we are unable to offer visa sponsorship.