Senior Software Development Engineer in Test

Location: Belfast, Northern Ireland, United Kingdom

Job Title: Senior Software Development Engineer in Test (SDET) 
Location: Belfast, Northern Ireland 
Work Arrangement: Hybrid

Position Overview: We are seeking an experienced Senior Software Development Engineer in Test (SDET) to act as a catalyst for quality across our engineering organisation. You will be a first-class engineer who builds & maintains our automated testing infrastructure, enabling rapid feedback cycles and the delivery of high-quality software at speed. This is a technical leadership role: you will advocate for quality throughout the software development lifecycle, design test strategies, influence our test architecture, mentor others in test automation, and partner with engineering teams to build quality in from the ground up rather than test it at the end.

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.

If you are passionate about quality engineering, comfortable using AI tooling to work faster and smarter, and want to shape testing practice in a fast-paced fintech environment, we want you on our team. 

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: 

• Test Architecture: Design and implement scalable test automation frameworks that enable rapid feedback and continuous testing 
• Quality Engineering: Partner with development teams to build quality into the development process through test automation, code reviews, and best practices 
• Innovation: Research and implement new testing tools and methodologies, including AI and agentic engineering approaches, to improve our testing efficiency and coverage 
• Continuous Improvement: Lead initiatives to enhance our testing infrastructure, practices and metrics to drive quality improvements 
• Technical Leadership: Mentor team members in test automation best practices and quality engineering principles 
• Perform other duties required by Management 

Essential Criteria:

• BSc or MSc in Computer Science, Software Engineering or related field OR equivalent commercial experience 
• Minimum 5 years of software testing experience in SaaS environments 
• Strong proficiency in at least one object-oriented programming language, ideally C#, though strong OO fundamentals in Java, Python or a similar language are equally welcome 
• Extensive hands-on experience with test automation frameworks and tools (e.g. NUnit, xUnit, Moq, SpecFlow/Reqnroll, or the equivalents in your language of choice) 
• Experience with API testing tools and techniques (e.g. Postman, RestSharp) 
• Experience with UI/browser automation (e.g. Playwright, Selenium) 
• Practical experience working with AI and agentic engineering processes 
• Working knowledge of SQL and database testing 
• Familiarity with CI/CD pipelines and tools 
• Experience of cloud technologies such as Azure/AWS/GCP 
• Proficient with Git and related workflows 
• Strong attention to detail and work ethic 
• Strong analytical and problem-solving skills 
• Excellent communication (both written and verbal) and interpersonal skills 
• Ability to work effectively with cross-functional teams 
• Legal right to work in the UK 

Desirable Criteria:

• Proficient with Claude or Claude Code 
• Experience with performance testing frameworks and tools (e.g. k6, JMeter, NBomber) 
• Knowledge of security testing principles and tools 
• Experience with test data generation and management 
• Experience of LEAN software development practices 
• Experience with Azure Functions and Queues 
• ISTQB Advanced Level or relevant technical certifications 
• Experience in the Financial services industry 
• Experience mentoring engineers or leading a test/QA function 

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. 

Please note we are unable to offer visa sponsorship.