Experienced Full Stack .NET Engineer

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 2028.

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 3 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) 

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: 

• Comprehensive Medical, Dental, and Vision Plans
• 401k with up to 4% company match
• Flexible open paid time off (PTO)

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

Our Core Values: 

How We Work: Our engineers work with agents and harnesses as a default, not an experiment. Our interview process includes a practical exercise 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 is likely not the right fit. 

Please note we are unable to offer visa sponsorship.