Back-End Developer (Java/Spring, Release & Operations Support)

About the project:

We’re looking for two Back-End Developers (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, bi-weekly demos, 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, 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; Dutch is not required

• 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:

1. Pre-screening with a Talent Acquisition Specialist

2. English check

3. Technical screening and evaluation with Techstack engineers

4. Candidate profile submission to the client