Senior Fullstack Engineer – Kotlin & React, API-First

LATAM; Poland; Hybrid; PLN 180,000 - 240,000; Full time

Job summary

Xebia is seeking a senior API and integration engineer to design and deliver backend services and modern web applications using Java, Kotlin, React, and TypeScript. You will lead architectural choices, define API contracts, and promote coding standards across distributed systems for client projects in the EU.

The role includes occasional office visits in Warsaw (1–2 times per quarter) and EU work-permitting requirements, with a hybrid work arrangement active in Poland.

Qualifications

• Strong commercial experience with Java and Kotlin.
• Proven REST API design and maintenance.
• Hands-on OpenAPI / Swagger experience.
• Very good React and TypeScript knowledge.
• Solid distributed systems and system integrations.
• OAuth 2.0 and OpenID Connect expertise.
• Experience using AI assistants to improve productivity.
• Experience making architectural decisions and leading technical discussions.
• Experience defining development standards and providing technical leadership.
• English B2 and Polish B1 levels.
• Willingness to visit client office in Warsaw quarterly.
• Work permit for EU region.

Responsibilities

• Designing and developing APIs enabling integrations with external business partners.
• Taking a technical lead in integration architecture and contributing to key architectural decisions.
• Defining API contracts and following an API-first approach using OpenAPI / Swagger.
• Developing backend services using Java and Kotlin.
• Building modern web applications using React and TypeScript.
• Defining and promoting software development standards and best practices.
• Preparing and maintaining technical documentation.
• Leading technical discussions and supporting the team in making sound engineering decisions.
• Working with distributed systems and complex system integrations.
• Participating in the on-call rotation.

Skills

Java

Kotlin

REST APIs

OpenAPI/Swagger

React

TypeScript

OAuth 2.0

OpenID Connect

Distributed systems

English B2

Polish B1

Tools

AWS

Azure

GCP

Databricks

Snowflake

Job description

Xebia is seeking a senior API and integration engineer to design and deliver backend services and modern web applications using Java, Kotlin, React, and TypeScript. You will lead architectural choices, define API contracts, and promote coding standards across distributed systems for client projects in the EU.

The role includes occasional office visits in Warsaw (1–2 times per quarter) and EU work-permitting requirements, with a hybrid work arrangement active in Poland.