The Role We are seeking a highly skilled Full Stack Developer based in Poland or Germany to design, build, and maintain systems that calculate, validate and distribute financial invoice data within the logistics and repair services domain. This role focuses on ensuring accurate billing between service partners and customers, while supporting approval workflows and compliance requirements. The developer will collaborate closely with Finance, Operations, Data and Partner Management teams to deliver high-quality, scalable solutions. A key part of this role is to enhance and extend an existing billing engine and onboard additional customers from new business areas, ensuring scalability and future readiness. The position requires strong communication abilities in English and Polish, as the developer will collaborate with international teams operating in both languages. Your Responsibilities Billing & Invoice Data Processing - Design and implement backend services for invoice data extraction, validation, calculation, and transformation based on contractual rules, SLAs, pricing matrices and repair service conditions. - Develop logic to consolidate data from logistics events, repair operations, partner services and external financial inputs. - Ensure accurate settlement and reconciliation between partners (e.g., repair centers, logistics providers) and customers. - Maintain audit trails and financial data integrity across the entire billing workflow. Approval & Workflow Automation - Build configurable approval workflows for internal and external stakeholders (e.g., finance controllers, partner managers, customer approvers). - Implement rule engines for exception handling, dispute management and manual overrides. - Provide UI features for reviewing, commenting, and approving billing items and invoice lines. System Architecture & Full Stack Development - Develop scalable solutions that support onboarding of new customers and business areas. - Design, develop and maintain robust backend APIs (REST) and microservices supporting billing and invoicing features. - Create and modernize intuitive front-end interfaces for financial reporting, approval monitoring, dispute resolution, and invoice line-item inspection. - Ensure seamless integration with operational systems, logistics platforms and finance systems. - Contribute to database schema design focusing on financial accuracy, performance and auditability. Data Quality, Compliance & Security - Implement and maintain validation frameworks ensuring high data accuracy across billing sources. - Ensure compliance with financial regulations, tax rules, customer/partner contracts and data protection requirements. - Build monitoring and alerting systems to detect anomalies in pricing, invoice volumes or approval delays. Collaboration & Stakeholder Management - Work closely with Finance, Operations, Partner Management and Data Engineering teams to improve billing performance and accuracy. - Translate business requirements into technical specifications, workflows and architecture components. - Support internal and external audits through transparent documentation and traceable system behaviour. Your Profile Technical Skills - Strong proficiency in full-stack development (e.g., TypeScript/Node.js, Java, Python, C#, or similar backend languages; React, Angular or Vue for frontend). - Experience with relational databases (MySQL, PostgreSQL is an advantage) and data modelling for financial transactions. - Knowledge of microservice architectures, API design, message queues and integration patterns. - Experience with cloud platforms (AWS), GitLab and CI/CD pipelines. Domain Knowledge - Understanding of invoicing, billing rules, tax logic and financial reconciliation processes. - Experience in logistics, repair services, or supply chain is a plus. - Knowledge of approval workflows and audit-compliance workflows. Language Skills - Fluent English (required) - for business communication, documentation and interaction with international stakeholders. - Fluent Polish (required) - for collaboration with Polish-speaking technical teams and operational stakeholders. Soft Skills - Agile mindset, embracing iterative development, continuous improvement, transparency and collaboration. - Strong analytical and problem-solving abilities, with high attention to financial accuracy. - Ability to work cross-functionally and translate complex requirements into scalable technical solutions. - Clear communication skills for stakeholder discussions and documentation. Location You should be based in Germany or Poland. This a full Home office-based position What We Offer - A versatile area of responsibility with which you are at the pulse of the company with the opportunity to influence crucial decisions - A flexible inclusive working environment - A multi-cultural operating company - An open-minded, positive and motivated environment with flat hierarchies and short decision paths - The ability to work independently and responsibly and contribute your talents - Colleagues which are more than happy to welcome you Your application Please send your CV in English.