Senior Full Stack Software Engineer - Payments

The Opportunity

We are seeking a seasoned Senior Full Stack Software Engineer to join our high-impact Payments Engineering team. In this role, you’ll help drive the evolution of our payment platform, supporting global payment flows including bank integrations, policy premium collections, refund processing, and Stripe/PSP integrations. You’ll work across the stack to build scalable APIs, intuitive user interfaces, and robust automation pipelines that power mission-critical financial transactions.

We’re building modern, cloud-native systems using .NET/C#, Azure SQL, and Vue.js, with a strong focus on automation-first development, security, and high availability. If you have experience in the payments domain, including payment gateways, reconciliation, and transaction workflows, this is an opportunity to make a direct impact on systems that process millions in revenue and support global policyholders.

Why Join Us?

This is a pivotal role in a growing, global organization that is transforming the way customers procure life insurance. You’ll contribute to a platform that manages payment lifecycle flows end-to-end — from initial premium collection and recurring billing, to refunds, chargeback handling, and bank API integrations (e.g., BACS, ACH, SEPA).

You’ll be empowered to shape system architecture, influence DevOps practices, and help standardize our integration with third-party payment providers like Stripe, GoCardless, and regional banks. Join an engineering culture that values automation, scalability, and inclusive collaboration.

Key Responsibilities

Full-Stack Payments Engineering

• Design and develop scalable, secure REST APIs in .NET/C# for payment-related services.
• Build responsive UIs using Vue.js for managing payment flows (e.g., policy billing, refunds).
• Develop integrations with external payment providers (e.g., Stripe, GoCardless) and bank APIs (e.g., UK BACS, AUS Westpac, ACH, etc.).
• Manage secure storage and transmission of payment data (PCI-DSS compliance awareness preferred).
• Handle edge cases including payment failure handling, retries, and reconciliation logic.

Automation and Quality

• Champion automation-first development: implement end-to-end testing using tools like SpecFlow, Playwright, and Gherkin.
• Contribute to test frameworks that ensure the accuracy of payment and refund logic.
• Lead code reviews and advocate for TDD/BDD practices across the team.

Platform Reliability and Observability

• Implement and maintain CI/CD pipelines for frequent, safe releases.
• Develop observability tooling to monitor payment transaction health, failures, and latency.
• Participate in post-incident reviews and contribute to system hardening initiatives.

Domain Collaboration

• Work closely with Product, Compliance, and Finance to ensure secure and compliant handling of funds.
• Support premium lifecycle operations, including initial billing, renewals, partial payments, and cancellations.
• Help develop and maintain refund processing workflows, including pro-rata calculations, reversals, and audit trails.

Required Qualifications

• Senior level software engineering competency, with strong full-stack experience.
• Proficient in .NET/C#, JavaScript, Azure SQL (MSSQL).
• Proven experience developing APIs and UI components in distributed systems.
• Experience working with payment systems (Stripe, BACS, ACH, GoCardless, etc.).
• Strong knowledge of test automation frameworks and CI/CD practices.
• Solid understanding of transaction integrity, idempotency, and financial system safety.

Preferred Qualifications

• Experience with Azure Cloud, Kubernetes, and containerized deployments.
• Familiarity with policy premium billing systems, insurance domain, or subscription management.
• Knowledge of financial reconciliation processes and ledger balancing.
• Background in security best practices related to handling sensitive payment data (e.g., tokenization, PCI compliance).
• Strong communication and mentoring capabilities.

About Neilson

At Neilson, our mission is to make life insurance simple, secure, and globally accessible. Since 2012, we’ve grown from a UK-based startup to a multinational leader in digital insurance services, operating across the UK, USA, Canada, Ireland, and Australia with over 1000 employees.

We Offer

Neilson provides a competitive total compensation package, extensive learning opportunities, and a dynamic environment where you can grow your career. Compensation will be based on experience, skill set, and business needs. Additionally, we offer a robust benefits package, including:

• 100% remote-first role with flexible working options
• Pension, healthcare, life assurance
• Great central office, only 2 minutes away from Windsor train station!
• Amazing bunch of people that genuinely want to support you and celebrate your wins!
• We work hard but we know how to have fun too; we have regular theme days and charity events for all to enjoy.
• Fancy a morning brew? We have that covered! Tea, coffee and milk provided!
• Employee Assistance Programme to help and support with life stuff!
• We have plenty of local discounts for coffee outlets, restaurants, cinemas and gyms and more
• Free fruit, Flu Vaccinations, Cycle to work scheme, Eye Test/Glasses Vouchers, looking after your wellbeing!
• 25 days holiday plus bank holidays

If you’re a driven leader with a passion for engineering and team empowerment, we want to hear from you. Join us at Neilson and help shape the future of our technology landscape.