Senior Full-Stack Engineer (React + Java)
First seen by Alion on Nov 10, 2026.
About the project:
We’re looking for a Senior Full-Stack Developer (frontend focus) to join a project for a Dutch bookkeeping platform that is modernizing its accounting core: moving from legacy single-entry logic to a database-backed double-entry model, with better ledger-code management and reconciliation. The live platform stays fully operational, so all changes are delivered safely within the existing architecture, together with the client’s engineering team.
This is a frontend-focused role: React and production MobX experience are the core, while Java/Spring knowledge helps you deliver features end to end. Full-time, approximately 6 months.
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.
Your team:
You’ll join an established Techstack team and work closely with the client’s internal engineers. The team includes a Project Manager, Lead Software Engineer, QA Engineer, Senior Full-Stack Developer (this position), 2 Back-End Developers, plus the client’s Solution Architect and CTO. We work through daily stand-ups, sprint reports, regular code reviews, and close communication with the client’s developers.
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:
Frontend: React, MobX, TypeScript, JavaScript
Backend: Java, Spring, Hibernate, JPA, Redis
Database: MariaDB, PostgreSQL, Flyway
Testing: API/Cucumber, JUnit 5, WireMock, frontend/browser testing
CI/CD & hosting: SonarCloud, CI pipelines, Docker, Linux, WAR deployment, AWS S3
Tools: Jira, Confluence, Miro, Slack, Figma
Practices: feature flags, code reviews, small PRs, regular releases
Your responsibilities:
Develop and maintain features in existing React/MobX applications used by clients and bookkeepers
Build administrative and configuration interfaces for ledger management and accounting workflows
Implement searchable lists, forms with validation, role-based permissions, and reconciliation views
Integrate frontend functionality with existing Java/Spring back-end APIs
Support back-end development when needed for end-to-end delivery
Make sure changes do not disrupt existing functionality in the live production platform
Write and maintain frontend and browser-level automated tests
Deliver changes through focused pull requests, feature flags, and regular releases
Collaborate with the Tech Lead, back-end developers, QA, PM, and the client’s engineering team
Participate in code reviews, daily stand-ups, demos, and acceptance testing
It’s about you:
Strong commercial experience with React, TypeScript, and JavaScript
Hands-on production experience with MobX
Working knowledge of Java and Spring for end-to-end feature development
Experience building admin/configuration interfaces, searchable lists, forms with validation, and role-based access
Experience working with large existing codebases and maintaining backward compatibility
Experience with feature flags, CI/CD, and small, focused pull requests
Experience writing frontend and browser-level tests
Ability to follow established architecture guidelines and collaborate through the client’s code reviews
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
Experience with MariaDB, Hibernate, and Flyway
Experience working with European clients
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 interview and evaluation with Techstack engineers
Candidate profile submission to the client
Technical interview with the client’s engineering representatives (if requested)