Java Backend Engineer

About the role

Behind every app we ship is a set of backend modules: accounts and ledgers, payments and payouts, card issuing, KYC, order matching and custody. They are written in Java, they run in production, and they are reused from one platform to the next.

You will design and build these services, and the integrations with banks, card processors, payment providers and blockchain networks. You will think about idempotency, consistency and audit trails as much as about features, because a payment processed twice is a bug that costs real money.

You will work in a small team with mobile, web and DevOps engineers, and you will have a real say in how the platform evolves.

What you will do

• Design, build and run backend services in Java and Spring Boot for our payment, banking, card and exchange platforms
• Model money correctly: double-entry ledgers, idempotent APIs, reconciliation and audit trails
• Integrate with banks, card issuers, payment processors, KYC providers and blockchain networks
• Write clear, documented and tested APIs for our mobile and web apps
• Keep services observable, secure and fast in production, and help fix them when they are not
• Review code and help decide how the platform evolves

What we look for

• 4+ years building backend systems in Java (17 or newer) with Spring Boot
• Strong SQL and PostgreSQL (or a similar relational database), including transactions and data modelling
• Experience with message queues or event streaming: Kafka, RabbitMQ or similar
• REST API design, authentication and authorisation (OAuth 2.0, JWT)
• Automated testing as a habit, and comfort with Docker and CI pipelines
• Good written English

Nice to have

• Payments, banking, card issuing or trading systems
• Crypto: wallets, custody, blockchain nodes or exchange matching engines
• Security and compliance standards such as PCI DSS or PSD2
• Kotlin, gRPC, or running services on Kubernetes