Senior Backend Engineer – Java / Kotlin

Senior Backend Engineer – Java / Kotlin

Banking & Investment Technology | High-Volume Financial Systems

The Mission

West Code is hiring experienced backend engineers for technology projects with banks, investment firms and other financial institutions. We are looking for people who have already worked in complex, regulated or high-volume financial environments and understand that reliability, data consistency and production ownership matter as much as clean code.

Depending on the project, you may work on investment-banking platforms, transaction-processing systems, risk and position services, market-data platforms, core banking components or other business-critical backend services.

What You’ll Build

• backend services using Java and/or Kotlin

• Spring Boot-based microservices and APIs

• event-driven and distributed systems

• high-volume transactional and data-processing services

• integration layers connecting internal and external financial systems

• services where consistency, resilience and auditability are critical

• production-ready systems designed for scale, high availability and observability

• technical solutions developed together with senior engineers, architects and business stakeholders

Must Have

• 5+ years of backend engineering experience

• strong Java and/or Kotlin

• Spring Boot and microservice architectures

• Kafka or another event-streaming / messaging platform

• REST APIs and system integrations

• SQL / PostgreSQL or another relational database

• Docker and CI/CD

• experience with production systems and incident / failure handling

• good English

• ability to work independently and take technical ownership

Strong Advantage

• commercial experience in banking, investment banking, capital markets or another regulated financial environment

• high-throughput or latency-sensitive systems

• trading, market data, positions, risk, pricing or post-trade systems

• core banking, ledger or transaction-processing platforms

• distributed consistency, idempotency and failure-recovery patterns

• Kubernetes and AWS / Azure / GCP

• OpenTelemetry, Prometheus, Grafana or similar observability tooling

• experience working with security, audit or regulatory requirements

Engineering Environment

Java / Kotlin · Spring Boot · Kafka · PostgreSQL · Docker · Kubernetes · Cloud · REST APIs · OpenTelemetry · CI/CD

Working Model

• B2B cooperation

• remote or hybrid work depending on the project

• projects for banks, investment firms and financial-services organisations

• international engineering environments

• English used on most projects

B2B Rate

170–220 PLN/h + VAT

Final rate depends on seniority, domain experience and project scope.

Why West Code

West Code builds engineering teams around ownership and strong technical delivery, not just individual roles. We are developing a dedicated business unit focused on technology projects for banks, investment firms and other financial-services organisations.

You’ll work on systems where scale, reliability and business context genuinely matter, with direct access to experienced technical leadership and practical AI-assisted engineering workflows supporting quality, requirements context and knowledge transfer.

If you have already built serious financial systems and want to work on projects where backend engineering has real business impact, apply and let’s talk.