Senior Fullstack Engineer (Java&Kotlin + JavaScript)

We are The Codest, an international tech software company with tech hubs in Poland delivering global IT solutions and projects. Our expertise centers on web development, cloud engineering, DevOps, and quality. We have developed the product Yieldbird, a laureate of the Top25 Deloitte awards. Our mission is to help tech companies build impactful products and scale their IT teams by boosting IT delivery performance. The project involves working with one of the largest e-commerce platforms in Europe, focusing on the New Ventures Core Tech area that launches innovative services with external strategic partners. The engineer will act as a technical leader and architectural anchor for partner integrations.

• Deep, hands-on experience in Java and Kotlin.
• Strong track record in designing, building, and scaling RESTful APIs with API-first design and OpenAPI/Swagger.
• Excellent frontend skills with proficiency in modern JavaScript/TypeScript and modern frameworks (preferably React).
• Solid understanding of distributed systems, integration patterns, and secure authentication protocols (OAuth 2.0, OpenID Connect).
• Proven ability to define coding standards, lead technical discussions, and design flexible API contracts for external B2B partners.
• English language skills at minimum B2+ level.
• Availability for Incident Response service.

Nice to have:

• Experience with data isolation and security standards.
• Interest in exploring and implementing Agentic AI tools (e.g., Copilot, LangGraph) to accelerate engineering workflows.

• Facilitate onboarding of external partners by designing robust API contracts and writing high-quality developer documentation.
• Create mock environments for API integration.
• Develop modern web interfaces such as checkout paths, landing pages, and discovery hubs consuming integrated partner services.
• Provide technical leadership bridging backend Java design with frontend development for cohesive end-to-end implementation.

Only candidates who are citizens of the European Union are eligible to apply.