Staff Software Engineer in Belfast

Apex Fintech Solutions (Apex) powers innovation and the future of digital wealth management by building tech-forward solutions that help simplify, automate, and facilitate access to financial markets for all. Our robust suite of fintech software enables us to support clients such as Stash, Betterment, SoFi, Webull, and eToro, amongst many others; collectively, Apex powers access to the stock market for over 22+ million end customers.

At Apex, we are changing how the securities industry operates by reinventing the status quo, which was manual, slow, and accessible only by the ultra-wealthy. We’re digitizing and democratizing systems so that everyone has an opportunity to invest. When you’re at Apex, you drive this change. You’re part of a global team with a clear vision: to be the trusted technology that powers the digital economy. Our offices in Austin, Dallas, Chicago, New York, Portland, Belfast, and Manila are home to over 1,000 employees. Together, we’re shaping the future of financial innovation. Embrace change. Solve big. Win together. And be G.R.E.A.T. — grit, results, empathy, accountability, and teamwork — with Apex.

We’re proud to be recognized for the innovative work we do, the purpose-driven nature of our work, and the collaborative culture we’ve created. Here are just a few of the many awards we’ve recently received:

• Best Places to Work 2026, 2025, 2024, 2023 Presented by BuiltIn
• WealthTech of the Year 2025 Presented by US FinTech Awards
• The World’s Top 250 Fintech Companies 2024 Presented by CNBC

We’re seeking an innovative, passionate, and forward-thinking individual to join us as a Staff Software Engineer. This is an opportunity to join a fast-paced team with the urgency of a startup and the expertise of an established organisation. Due to the space we innovate in, your products will process billions of transactions per day in real-time and power both startup and established industry participants.

As a Staff Platform Engineer in this multi-disciplinary team, you will play an integral role in designing, implementing, and optimizing our Billing services, tooling, and infrastructure to ensure robust, scalable and accurate billing to our clients.

Duties/Responsibilities

• Design and evolve microservices architecture for the billing platform, ensuring scalability, reliability, and maintainability across the distributed system.
• Lead technical decision-making for complex billing workflows involving rate configurations, charge calculations, settlement generation, and end-customer processing, balancing business requirements with system performance and cost constraints.
• Drive performance optimization of data-intensive operations leveraging BigQuery, PostgreSQL, and caching strategies to handle high-volume financial calculations and reporting at scale.
• Mentor and guide engineers across multiple teams, establishing best practices for Java development, Bazel build configurations, database migrations with Flyway, and event-driven architectures.
• Own system reliability and operational excellence, implementing comprehensive monitoring with Datadog, designing robust error handling and validation, and ensuring SLOs are met for critical financial processes.
• Collaborate cross-functionally with product, finance, and compliance teams to translate business requirements into technical solutions, managing integrations with external financial systems and internal platform services.
• Establish and maintain technical standards for the billing domain, including testing strategies, API design with gRPC and Protobuf, database schema evolution, and deployment practices across multiple environments.

Education and/or Experience

• Bachelor's degree in Computer Science, Engineering, or related field (or equivalent work experience) required; advanced degree preferred.
• 8+ years of experience in software development with a deep knowledge in one or more programming languages, including Java, Python.
• Experience with automated testing frameworks and methodologies for backend services.
• Experience contributing to topics and participating in technical direction and implementation strategy for projects.
• Experience with CI/CD (Continuous Integration/Continuous Deployment) pipelines and tools, automating build, test, and deployment processes.
• Experience with cloud platforms (e.g., AWS, Azure, GCP).
• Experience with SQL including the ability to write complex queries and optimise database performance, e.g. Postgres, MS SQL Server.
• Experience in financial services a plus.

Required Skills/Abilities

• Expertise with containerization (Docker), orchestration (Kubernetes), cloud platforms (GCP, AWS), and infrastructure automation (Terraform, Ansible).
• Expertise in software release tooling, GitOps, and CI/CD practices.
• Excellent communication skills and the ability to collaborate effectively with cross-functional teams.
• Knowledge of API management methodologies, security practices, and traffic management strategies.

Work Environment

This job operates in a hybrid, office environment 2 days per week.

Our Rewards

We offer a robust package of employee perks and benefits, including a market-leading salary with an annual bonus, 28 days of annual leave plus 10 Northern Ireland national holidays, a training and development budget, and a pension matched up to 7%. Our benefits also cover private health insurance for medical, dental, and optical care, and life insurance. We emphasize work-life balance with flexible working hours, parental leave, a modern city center office, and a hybrid work schedule that allows for greater flexibility by partially working from home. Additional perks include monthly catered lunches, unlimited drinks and snacks, hackathon events, poker tournaments, and a charitable matching gift program.

EEO Statement

Apex Fintech Solutions is an equal opportunity employer that does not discriminate on the basis of race, color, religion, sex (including pregnancy, sexual orientation, and gender identity), national origin, age, disability, veteran status, marital status, or any other protected characteristic. Our hiring practices ensure that all qualified applicants receive fair consideration without regard to these characteristics.

Disability Statement

Apex Fintech Solutions is committed to creating an inclusive and accessible workplace for all candidates, including those with disabilities. We are dedicated to ensuring equal employment opportunities and providing reasonable accommodations to qualified individuals with disabilities. If you require reasonable accommodations to participate in the application or interview process, please submit your request via the Candidate Accommodation Requests Form. We will work with you to provide the necessary accommodations to ensure your full participation in our hiring process.