Experienced 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

Auto-enrollment pension with employer

25 days holiday per year

10 statutory/bank holidays per year

Opportunities for professional growth

Collaborative and innovative work env

Job summary

Biller Genie is seeking an experienced AI-enabled .NET full-stack engineer to join our Belfast team. You will quickly understand our codebase and drive complex fintech features from conception to deployment in a hybrid setup.

As a key member of the engineering team, you will own significant features, collaborate with senior engineers, and help shape the AI-powered developer experience by embedding AI tooling throughout our platform.

Qualifications

• BSc or MSc in Computer Science / related qualification OR commercial experience of developing in C#, Java or other OO programming languages.
• Minimum 5years of hands-on commercial experience programming on the .NET platform using C#, including ASP.NET (MVC).
• Experience with Design Patterns, refactoring, OODesign and 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

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

Skills

C#

ASP.NET

OO design

Java

Design Patterns

HTML/JS/CSS

SQL/Database design

Cloud (Azure/AWS/GCP)

Git

Web API

Education

BSc or MSc in Computer Science

Tools

Git

Azure Functions

Queues

Job description

Belfast, Northern Ireland, United Kingdom

Job Title: ExperiencedFull Stack .NET Engineer
Location: Belfast, Northern Ireland
Work Arrangement: Hybrid
Position Overview: We are seeking an experiencedAI-enabled.NET full-stack engineer 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 experienceandexpertisewill be vital in delivering high-quality, robust solutions. Join our growing team and make a substantial impact on our platform!

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 5years 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 practices
• Hands-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

About Us:

Biller Genie is an award-winning B2B SaaS platform, recently ranked #516 on the Inc. 5000 list of the fastest-growing companies in the United States. With headquarters in Orlando and a growing Engineering Hub in Belfast, we're scaling fast, with over 100 hires planned through 2028.

Our Mission:

To provide an automated A/R platform that seamlessly integrates existing business processes for the SMB market.

Our Core Values:

Get S**t 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.

Biller Genie is an equal opportunity employer. We celebrate diversity and make all employment decisions without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, veteran status, disability status, age, or any other status protected by law.

Please note we are unable to offer visa sponsorship.