Middle Java Software Engineer

Back-End Enginner (Java/Spring, Release & Operations Support)
Start & timeline:
We’re hiring in advance. The project is currently in Phase 2, and the role starts with Phase 3, expected in early January 2027 (exact date TBC). We’ll keep you updated throughout the hiring process.
About the project:
We’re looking for two Java Engineers (Middle+ / Senior level) to join our team on a project for a Dutch bookkeeping platform. The product is modernizing its accounting core: replacing legacy single-entry accounting logic with a database-backed double-entry model, improving ledger-code management, and introducing reliable reconciliation capabilities.
All changes are implemented within the existing Java/Spring application, with a strong focus on production stability, preserving historical accounting data, and safe migration to the new model. The current platform must keep running without disruption. This is a full-time engagement for approximately 19–23 weeks (Phases 3–4).
Your team:
You’ll join an established Techstack engineering team and work closely with the client’s internal developers and technical stakeholders. The team includes a Project Manager, Lead Software Engineer, QA Engineer, Senior Full-Stack Developer, and 2 Back-End Developers (these positions), plus the client’s Solution Architect and CTO. We work through daily stand-ups, sprint reports, regular code reviews, and close collaboration with the client’s engineering team.
Culture:
We uphold high standards in the tech industry and continuously evolve to meet them. Every team member can influence the product, the company, internal processes, and their own professional growth. We also regularly organize team-building activities to keep a friendly atmosphere and simply enjoy time together.
Technical stack:
Backend: Java, Spring, Hibernate (monolith), JPA, Redis
Database: MariaDB, PostgreSQL, Flyway migrations
Testing & quality: JUnit 5, WireMock, API/Cucumber tests, CI, SonarCloud
Hosting & deployment: Linux, WAR deployment, Docker (local/CI), AWS S3
Integrations: third-party payroll and banking APIs, tax authority APIs, OpenAI, Mailgun
Delivery practices: feature flags, regular releases, roll-forward fixes
Frontend (awareness only): React, MobX, TypeScript, JavaScript
Tools: Jira, Confluence, Miro, Slack, Figma
Your responsibilities:
Develop back-end functionality within the existing Java/Spring monolith: APIs, business logic, and data models
Design and modify database schemas; implement safe schema and data migrations
Implement accounting logic with strong data-integrity requirements: balanced entries, auditability, and no data loss
Develop role-based access controls for new functionality
Build and maintain reconciliation and validation tools to compare the new accounting logic with existing system behavior
Write unit and integration tests and keep regression suites green
Support production releases: CI pipelines, feature flags, deployments, and post-release monitoring
Investigate application logs and help troubleshoot deployment and production issues
Work closely with the Tech Lead, back-end and front-end developers, QA, PM, and the client’s engineering team
Participate in code reviews and maintain technical documentation
It’s about you:
Solid commercial experience with Java
Hands-on production experience with Spring and Hibernate
Strong SQL skills and relational database design, preferably MariaDB or MySQL
Experience with schema and data migrations using Flyway or similar tools
Good understanding of transactions, database constraints, data integrity, and idempotent operations
Experience writing unit and integration tests (JUnit 5, WireMock, or similar)
Experience maintaining and extending large existing codebases without breaking functionality
Familiarity with feature flags, small focused PRs, and CI pipelines
Comfortable working with Linux, application logs, and supporting production releases; hands-on experience with deployments, troubleshooting, and post-release monitoring is highly valued
Ability to follow established architecture standards and collaborate through code reviews with the client’s developers
Good spoken and written English for daily communication with the client
Time zone: Europe/Kyiv or compatible with CET/CEST working hours
Would be a plus:
Experience in accounting, bookkeeping, or FinTech projects
Experience with dual-write, reconciliation, or data verification during migrations and data model changes
What we can offer you:
Full-time engagement (40h/week) on a product with a complex, high-integrity domain
Direct communication with all stakeholders, including the client’s engineering team
Broad opportunities for professional and career growth: challenges, meetups, hackathons, professional communities, and more
Horizontal connections and no micromanagement: all team members are accessible to each other for any questions
Hubs in Kharkiv, Kyiv, Lviv, and Wrocław (Poland), or everything necessary for remote work
Up to 50% compensation for educational courses and conferences
Free English and business English courses
20 days off and 7 sick days
Legal and accounting support
Appreciation gifts for significant events and occasions
How to join Techstack:
Pre-screening with a Talent Acquisition Specialist
English check
Technical screening and evaluation with Techstack engineers
Candidate profile submission to the client