Senior Software Engineer - Backend (FTC)

Role Purpose

As a Senior Backend Software Engineer (Fixed Term Contract) 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.

Focus: A fixed term engagement with a clearly scoped remit, embedded within a high-calibre engineering team operating on greenfield and core platform work.

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.

Benefits: Competitive day rate, flexible working arrangements, and Singapore-based team with global stakeholder exposure.