Experienced Full Stack .NET Engineer

Biller Genie; Belfast City District; Hybrid; GBP 70,000 - 100,000; Full time

Benefits offered by this job

Private health insurance

Group life death benefit

Auto-enrollment pension - 5% matched

25 days holiday per year

10 holidays per year

Professional growth opportunities

Collaborative work environment

Job summary

Biller Genie, an AI-enabled B2B SaaS company, seeks an experienced Full Stack .NET Engineer in Belfast with hybrid work arrangement. You should drive features from conception to deployment across the full stack, embracing AI tooling and agentic workflows.

The role requires strong C#, .NET, web tech, cloud familiarity, and a track record in fintech environments. You will own architecture and collaborate across the SDLC, shaping scalable solutions with impact.

Qualifications

• BSc or MSc in Computer Science / related field or commercial experience in C#, Java or other OO languages.
• Minimum 5 years of hands-on commercial experience on the .NET platform using C#, incl. ASP.NET MVC.
• Experience with Design Patterns and OO design.
• Hands-on experience with AI coding assistants and agentic engineering workflows.
• Exposure to Web API for building web services.
• Understanding of database design and development.
• HTML, JavaScript, CSS including jQuery experience.
• Strong attention to detail, analytical and communication skills.
• Experience with cloud tech (Azure/AWS/GCP) and source control (TFS/SVN/GIT).
• Legal right to work in the UK.

Responsibilities

• Design & build future-proof solutions, considering system impact.
• Collaborate with senior engineers to plan, estimate, and track progress.
• Gather requirements and release software in a timely fashion.
• Balance speed and efficiency; adapt as needed.
• Work with support to reproduce and fix bug tickets.
• Develop features via agentic tooling and improve skills/harnesses.
• Contribute prompts, skills, and workflow improvements to AI-enabled dev experience.
• Perform other duties as required by management.

Skills

C# / .NET

Java

OO design

AI coding assistants

Web API

HTML / JavaScript / CSS

jQuery

Azure / AWS / GCP

Git (source control)

Agentic engineering workflows

Education

BSc/MSc in Computer Science or related

Tools

Azure Functions

CI/CD

Claude

Git

Job description

Job Title: Experienced Full 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 ownership ofsignificant 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 2028.

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 5 years 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.