Senior/Lead Java Engineer

Location: Remote / Lviv
Role Type: Full-Time
Domain: B2B Marketplace & Tech-Enabled Logistics

About the Role
We are seeking a Senior Java Software Engineer to play a pivotal role in modernizing and scaling the digital engine powering our nationwide B2B wholesale marketplace and fulfillment logistics platform. In this role, you will lead the backend architectural transition from an established monolithic platform to a modern, high-throughput, event-driven Java microservices ecosystem. You will be responsible for re-architecting core transaction flows, establishing rigorous automated delivery pipelines together with DevOps team, and ensuring absolute data and financial integrity across inventory, order fulfillment, and multi-channel partner integrations.

Key Responsibilities

• Core Platform Architecture & Modernization: Design, build, and scale resilient Java microservices (Spring Boot / Java 21+) to replace legacy backend components, decoupling monolithic services into modular, domain-driven microservices.

• Transaction & Financial Integrity: Ensure bulletproof data integrity, idempotency, and transactional consistency across payment webhooks, customer billing, automated vendor payouts, and order ledger workflows.

• API & Multi-Tenant Access Control: Architect robust, high-performance REST APIs enforcing granular server-side Role-Based Access Control (RBAC) across distinct user personas (buyers, brand suppliers, logistics partners, and internal ops).

• Asynchronous & Event-Driven Pipelines: Build high-velocity, asynchronous message processing pipelines for real-time inventory synchronization, order state machines, transactional notifications, and third-party webhooks.

• AI-Assisted Engineering Efficiency: Leverage modern AI/LLM development tools (e.g., GitHub Actions, Claude Code, automated code reviews) to accelerate refactoring, test generation, and documentation

Required Technical Experience & Qualifications

1. Java Ecosystem & Microservices Expertise

• 5+ years of production experience with modern Java (Java 17 / 21) and the Spring Ecosystem (Spring Boot 3, Spring Data JPA, Spring Security, Spring Cloud).

• Deep understanding of Domain-Driven Design (DDD), clean architecture principles, and building high-throughput, low-latency B2B services.

• Demonstrated track record of decoupling monolithic codebases (e.g., Ruby on Rails, Node.js, or legacy monoliths) into modern, containerized Java microservices.

1. Data Engineering, Messaging & Storage

• Relational Database Mastery: Advanced experience with PostgreSQL (complex query optimization, connection pooling, ACID transaction management, indexing strategies, and schema migration tools.

• Caching & In-Memory Data Stores: Experience implementing multi-tier caching architectures using Redis for session management, rate limiting, and fast data retrieval.

• Event-Driven Architecture: Hands-on experience with asynchronous messaging frameworks (Kafka, RabbitMQ) and long-running workflow orchestration engines

1. API Design & Third-Party Integrations

• Proven experience building and consuming resilient, secure webhooks and REST APIs with external ecosystems (e.g., payment gateways like Stripe, EDI/Orderful, shipping & logistics APIs, ERP/Shopify connectors).

• Strong focus on defensive API engineering: rate limiting, circuit breaking, retry mechanisms, and cryptographic request verification.

Key Attributes & Culture Fit

• High Ownership & Pragmatism: Comfortable working in a lean, high-velocity engineering pod where developer autonomy, clear architecture, and measurable business outcomes are valued over bureaucracy.

• Financial & Operational Mindset: Deep appreciation for the real-world operational impact of software—treating every order, payout, and inventory update as mission-critical.

• AI-First Productivity: Eager to incorporate cutting-edge AI and LLM tools into daily development workflows to maximize velocity and code quality

We Offer

• Opportunity to propose solutions and influence technical decisions

• Dynamic and challenging tasks

• Team of experienced professionals

• Competitive salary

• Low bureaucracy

• Continuous self-improvement

• Long-term employment with paid vacation and social benefits

• A bunch of perks 😊