Senior Backend Engineer — Payments Microservices (Poland)

B3 Consulting Poland; Polska; Hybrid; PLN 180,000 - 260,000; Full time

Benefits offered by this job

Health and sports benefits

Speed Coaching

Sports training & internal team

Team events & meetups

Job summary

Senior Software Engineer at B3 Consulting Poland will design and scale backend microservices for the merchant payments domain, building core services for prepaid wallets, payment gateway integrations, invoicing, and reporting.

You will migrate legacy services to Clean Architecture and Hexagonal Architecture, build event-driven integrations over REST and Kafka with Avro, and own full lifecycle deployment using Helm, GitLab CI, and Kubernetes.

Qualifications

• Backend microservices with Java/Kotlin, Spring Boot, Clean/Hexagonal Architecture
• Event-driven with Kafka and Avro, REST integrations
• Knowledge of monetary calculations and PII protection
• Testing with Spock and Testcontainers
• GitOps and DevOps with Helm, GitLab CI, Kubernetes
• Experience with AI-assisted coding tools (Claude Code, GitHub Copilot, Cursor, Codex)

Responsibilities

• Design and deliver backend microservices in the merchant payments and reporting domain, including prepaid wallets, invoicing, and SAP / payment gateway integrations.
• Migrate legacy services to Clean Architecture and Hexagonal Architecture, documenting decisions with Architecture Decision Records.
• Build event-driven integrations over REST and Kafka with Avro, ensuring idempotency and correct money handling.
• Own full lifecycle deployment and quality using Helm, GitLab CI, GitOps on Kubernetes, and testing with Spock, Testcontainers, and Spring Cloud Contract.

Skills

Java/Kotlin

Spring Boot

Microservices

Clean Architecture

Hexagonal Architecture

Kafka

REST

Monetary calculations

PII protection

Spock/Testcontainers

GitOps

Kubernetes

DevOps practices

AI-assisted coding tools

agentic coding tools

Tools

Kafka

Avro

Spock

Testcontainers

Spring Cloud Contract

Helm

GitLab CI

Kubernetes

Claude Code

GitHub Copilot

Cursor

Codex

Job description

Senior Software Engineer at B3 Consulting Poland will design and scale backend microservices for the merchant payments domain, building core services for prepaid wallets, payment gateway integrations, invoicing, and reporting.

You will migrate legacy services to Clean Architecture and Hexagonal Architecture, build event-driven integrations over REST and Kafka with Avro, and own full lifecycle deployment using Helm, GitLab CI, and Kubernetes.