Senior Software Engineer - Backend

Build the payment infrastructure powering global commerce.

Boku connects billions of consumers to the payment methods they prefer, one market at a time. Our platform connects the world’s leading digital businesses to the local payment methods their customers already use. Spotify, Meta, Microsoft, Netflix and Tencent already run on Boku’s payment infrastructure. We operate across 60+ countries, support 200+ local payment methods and reach 7.5 billion consumer accounts.

With headquarters in London and San Francisco and colleagues working across markets around the world, Boku is global by default. From London to Mumbai, São Paulo to Singapore, our teams collaborate across time zones, markets and cultures to build products for customers around the world.

Join us to solve complex, real-time payment challenges at global scale. We share knowledge freely, take ownership of complexity and look for people who question how things are done and find better ways to build.

Role Purpose

As a Senior Backend Software Engineer within Boku’s Engineering organisation, you will be one of a small group of engineers delivering new products as part of Boku’s Innovation department. A new suite of products being built from the ground up. This is a greenfield development engagement: the work is scoped to designing and building new software, not maintaining or extending existing production services. You will work in a small, high-autonomy team with a clear remit and a defined delivery horizon, reporting to the Head of Product and Engineering.

Key Responsibilities

Backend Engineering

• Design and build production-grade services using Java and Spring Boot, targeting high throughput, low latency, and high availability (99.99%+).
• Implement and evolve RESTful/gRPC/MCP and event-driven APIs supporting payment initiation, callback handling, reconciliation, and settlement flows.
• Build for fault tolerance and resilience: circuit breakers, retry logic, idempotency, and graceful degradation under load. Maximum observability and telemetry at the core of the build to ensure easy support.
• Optimise service performance through profiling, load testing, and careful data access layer design (SQL and NoSQL).
• Collaborating with colleagues and off-shore development teams providing code-reviews and guidance as necessary to team members and development studios.

Payment Systems

• Build the core components of Payout, Card Processing and FX systems from scratch, including a payout processing engine, AI agent treasury orchestration layer, and cash forecasting service. This work is entirely new development and there is no existing codebase to maintain or inherit.
• Contribute to PCI DSS compliant system design and implementation, including sensitive data handling, audit logging, and access control.

Frontend Contribution

• Contribute React-based frontend components for internal tooling, operational dashboards, and merchant-facing interfaces where required.
• Work with Product and Design to deliver functional, well-tested UI features that meet Boku's quality bar.

FX & Treasury Integration (Desirable)

• Support integration with FX data sources including Bloomberg feeds, for use in real-time rate pricing, settlement FX, and treasury risk tooling.
• Contribute to cash position and FX exposure monitoring services, working alongside Finance and Treasury stakeholders.

Reliability & Operations

• Instrument projects with observability from day one: structured logging, distributed tracing, metrics, and alerting built as part of the product, not retrofitted. On-call and incident management for existing Boku production services are outside the scope of this contract.
• Instrument services with structured logging, distributed tracing, and metrics; contribute to SLO/SLA definitions and alerting.
• Set up CI/CD pipelines, container build configuration (Docker/EKS), and code quality gating (SonarCloud, SAST) as new infrastructure built to Boku’s engineering standards and handed over as part of the finished product.

Key Skills, Experience and Competencies

Required

• 5+ years of backend engineering experience, with deep expertise in Java and the Spring Boot ecosystem (Spring MVC, Spring Data, Spring Security).
• Demonstrable experience building and operating high-throughput, high-availability distributed payment or financial services systems.
• Strong understanding of payment system architecture: idempotency, exactly-once delivery, reconciliation, and settlement flows.
• Experience with relational databases (PostgreSQL, MySQL) and messaging systems (Kafka, RabbitMQ, or equivalent).
• Familiarity with container-based deployment (Docker, Kubernetes/EKS) and CI/CD pipeline tooling (GitHub Actions or equivalent).
• Experience with PCI DSS compliant system design and secure coding practices.
• Strong communication skills; ability to work effectively with Product, Architecture, and Operations in a globally distributed team.

Preferred

• React frontend development experience sufficient to contribute to internal tooling and dashboards.
• Experience integrating with Bloomberg data feeds (BFIX, B-PIPE, or similar) or other real-time FX data sources.
• Background in FX processing, treasury systems, or multi-currency settlement.
• Experience with financial messaging standards (ISO 20022, SWIFT MT/camt formats).
• Prior work in a payments processor, PSP, or fintech operating across multiple markets.

AI & Agentic Systems

• Practical experience building or integrating LLM-powered features into production services, including prompt engineering, tool/function calling, and structured output handling via APIs such as Anthropic or OpenAI. Familiarity with AWS Bedrock is ideal.
• Experience designing or contributing to agentic workflows: multi-step autonomous processes where models plan, call tools, and act on results — including handling retries, failure modes, and human-in-the-loop checkpoints.
• Familiarity with MCP (Model Context Protocol) or similar tool-use frameworks for connecting AI models to internal APIs, databases, and external services.
• Comfortable using AI-assisted development tooling (e.g. Claude Code, GitHub Copilot, Cursor) as part of day-to-day engineering workflow, and able to reason critically about where AI assistance adds value versus where it requires human judgement.

Qualifications

• Bachelor's degree in Computer Science, Engineering, or equivalent practical experience.
• 5+ years of professional software engineering experience in backend-heavy roles.
• Prior experience in a regulated financial services or payment processing environment strongly preferred.

Why Join Boku?

Impact: Work on payment infrastructure that processes billions of dollars annually, serving some of the world's largest digital commerce platforms across 65 countries.

Culture: A collaborative, inclusive engineering culture that values craft, rigorous thinking, and delivery. Boku is a genuinely global company with deep expertise in local payment markets.