Senior Java Developer

London, UKRemote

About the Role

NorthFjord Pay is seeking a Senior Java Developer to join their Payments Core squad in London, UK. This role offers a hybrid working model, allowing for two days per week in the Shoreditch office or fully remote work within UK/EU time zones (±2h CET). The position is permanent and full-time, reporting to the Engineering Manager of Payments Core. The salary band for this role ranges from £85,000 to £110,000 base, accompanied by a 10% annual bonus and equity.

Key Responsibilities

The Senior Java Developer will take on a hands-on technical role within the Payments Core squad, focusing primarily on designing and writing production code. Key responsibilities include:

Leading the design and delivery of a new card-authorisation routing service to replace a legacy module currently handling approximately 600 transactions per second (TPS) at peak.
Owning the migration plan, which includes dual-running, traffic shifting, and rollback strategies.
Driving a measurable reduction in p99 authorisation latency, with a current target of reducing it from 240 ms to under 150 ms.
Improving the squad's testing approach by introducing contract testing between Payments Core and three downstream services.
Participating in the on-call rotation for the services owned by the squad, approximately one week in every six, with compensation provided.

Required Qualifications

Candidates should possess the following qualifications:

Approximately 6+ years of professional backend development experience, with significant experience in Java in production-grade, high-availability environments.
Strong proficiency in Java (11+, ideally 17 or 21) and deep familiarity with the Spring ecosystem, including Spring Boot, Spring Data, and Spring Security.
Solid experience in designing and operating REST APIs and event-driven services using Kafka or a comparable broker (e.g., Pulsar or RabbitMQ).
Proficiency with relational databases, particularly PostgreSQL, including the ability to read an EXPLAIN plan, design sensible schemas, and reason about transactions and locking.
Hands-on experience running services in containers on Kubernetes, along with experience with at least one major cloud provider (AWS preferred).
A pragmatic approach to testing, including the ability to write unit, integration, and contract tests as part of normal work, and familiarity with tools such as JUnit 5, Mockito, and Testcontainers.
Experience in operating what you build, including reading dashboards, writing alerts, and debugging incidents in production.

Preferred Qualifications

While not required, the following qualifications are considered a plus:

Prior exposure to card schemes (Visa/Mastercard), ISO 8583, 3DS, or open banking.
Experience with Kotlin alongside Java.
Familiarity with Domain-Driven Design (DDD) and event sourcing.
Contributions to open-source projects or technical writing experience.

What We Offer

NorthFjord Pay provides a comprehensive benefits package, which includes:

25 days of holiday plus UK bank holidays.
Private health insurance through Bupa.
An annual learning budget of £1,500.
A home-office stipend.
An employer pension contribution of 6%.
Meaningful equity in a profitable and growing fintech company.