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

Techstack; United States; Híbrido; USD 69.000 - 103.000; Jornada completa

Descripción de la vacante

Techstack is seeking two Back-End Developers (Middle+ / Senior) to modernize a Dutch bookkeeping platform using a Java/Spring stack. The role focuses on production stability, data integrity, and safe migration to a new double-entry model, while the platform remains running without disruption.

This is a full-time engagement for about 19–23 weeks (Phases 3–4). You'll work with a team of engineers and stakeholders, participate in code reviews, and contribute to a robust CI/deploy process, including

Formación

• Strong SQL skills and relational database design.
• Experience with schema and data migrations (Flyway).
• Knowledge of transactions, data integrity, and idempotent ops.
• Experience writing unit/integration tests (JUnit 5, WireMock).
• Experience with deployments, CI pipelines, and production releases.

Responsabilidades

• Develop back-end functionality in Java/Spring monolith.
• Design/modify database schemas and migrations.
• Implement accounting logic with data integrity guarantees.
• Build RBAC for new functionality and reconcile data.
• Write tests and support release pipelines and monitoring.

Conocimientos

Strong SQL skills

Relational DB design

English communication

Collaborative teamwork

Herramientas

Flyway migrations

JUnit 5

WireMock

MariaDB/MySQL

Descripción del empleo

Back-End Engineer (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 product

Intro

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).

Backend: Java, Spring, Hibernate (monolith), JPA, Redis

Database: MariaDB, Flyway migrations

Integrations: third-party payroll and banking APIs, tax authority APIs, OpenAI, Mailgun

Delivery practices: feature flags, regular releases, roll-forward fixes

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 are committed to implementing high standards in the technology industry, and it is the fundamental mission of our work. To achieve this goal, the company and all its members are constantly evolving.

Each of us has the opportunity to contribute to the product, the company, the team, the industry, and our personal development. At Techstack, you have the option to choose from various growth opportunities that align with your interests:

• meetups, where you can share your knowledge and develop simultaneously by sharing your experiences within the company and local technical communities;
• roles such as a mentor or a technical lead. In any of these roles, you will assist junior professionals and share your knowledge and experiences with them.
• participation in our technical Guilds, where you can discuss technical solutions, approaches, and industry trends.

All of these elements contribute to shaping the culture and expertise within both our team and the company as a whole.

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

• 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.

Will 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 havefor you

• Stable and long-term position in an experienced team.
• Broad opportunities for professional and career growth, including professional challenges that encourage personal development, meetups, hackathons, professional communities, and more.
• Horizontal connections and the absence of micromanagement foster a collaborative environment in which all team members are accessible to one another for any concerns.
• Hubs in Kharkiv, Kyiv, Lviv, and Wrocław (Poland), or everything necessary for remote work.
• Up to 50% compensation for the cost of educational courses and conferences to support professional development.
• Free English language and business English courses.
• 20 days off and 7 sick days to support your health and well-being.
• Legal and accounting support.
• Appreciation gifts for significant events and occasions.

About us

Techstack is a technology product engineering company that sets an example for high development standards in the IT industry. We empower each team member to influence the development of the product, company, and processes.