Full Stack .NET Engineer

Biller Genie; Belfast City District; On-site; GBP 55,000 - 75,000; Full time

Job summary

Biller Genie in Belfast is seeking experienced AI-enabled .NET full-stack engineers who can quickly understand our codebase and contribute to complex fintech solutions across the SDLC in a hybrid in-office setting. You will join a growing AI-enabled engineering team, owning significant features from conception to deployment, and collaborating with senior engineers to deliver high-quality, robust software.

The role emphasizes architectural ownership, performance, and rapid delivery within a

Qualifications

• BSc or MSc in Computer Science or related qualification, or equivalent commercial experience.
• Minimum 2 years of hands-on commercial experience with .NET and C#, including ASP.NET (MVC).
• Experience with Design Patterns, refactoring and OO design.
• Experience with AI coding assistants and agentic engineering workflows.
• Experience building web services using Web API.
• Understanding of database design and development.
• Hands-on HTML, JavaScript, CSS including jQuery.
• Experience with cloud technologies (Azure/AWS/GCP).
• Experience with source control tools (TFS, SVN, or Git).
• Legal right to work in the UK.

Responsibilities

• Design and build future-proof solutions aligning with business needs.
• Collaborate with senior engineers to plan, estimate, and track progress.
• Gather requirements and release software promptly.
• Balance speed and efficiency in delivery.
• Identify, reproduce, and remediate bugs with the support team.
• Develop features using agentic tooling and AI capabilities.
• Contribute prompts and workflows to enhance the AI-enabled developer experience.
• Perform other duties as required by management.

Skills

C#

ASP.NET

Java

HTML

JavaScript

CSS

jQuery

Design Patterns

OO Design

Azure

AWS

GCP

Git

Problem Solving

Communication

Education

BSc/MSc in Computer Science or related

Job description

Job Information

Job Title: Full Stack .NET Engineer

Location: Belfast, Northern Ireland

Work Arrangement: Hybrid In-Office

Position Overview

We are seeking experienced AI-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 our engineering team, you will take ownership of significant 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 and expertise will be vital in delivering high-quality, robust solutions. Join our growing team and make a substantial impact on our platform!

About Us

Recently ranked #482 on 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, tracking and managing progress, risks, and dependencies.
• Gather and refine requirements, and release software in a timely fashion
• Be adaptive and strike a good balance between speed and efficiency
• Work with our technical support team to identify, 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#, Java or other OO programming languages
• Minimum 2 years of hands‑on commercial experience programming on the .NET platform using C#, including ASP.NET (MVC)
• Experience with Design Patterns, refactoring, OO Design and related areas
• Practical hands‑on experience with AI coding assistants and agentic engineering workflows, 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
• Previous experience 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