Senior Fullstack Engineer-API-First & Partner Integrations

Codest Ltd. Company No. 12590542, VAT number: GB363431020; Warszawa; On-site; PLN 223,000 - 290,000; Full time

Benefits offered by this job

Worksmile platform

Growth opportunities

Job summary

The Codest, an international tech software company with a footprint in Poland, is seeking an Engineer to lead API design and partner integrations for a major European e-commerce client. You will drive frontend development (checkout paths, landing pages) using JavaScript/TypeScript and React, while bridging Java backend and frontend efforts and shaping API contracts.

Ideal candidates have strong Java/Kotlin experience, OpenAPI/Swagger know-how, and a pragmatic approach to security and scalable

Qualifications

• Deep hands-on experience in Java and Kotlin.
• Strong API experience with RESTful APIs and OpenAPI/Swagger.
• Excellent frontend skills in JavaScript/TypeScript and React.
• Understanding of distributed systems and secure authentication (OAuth 2.0, OpenID Connect).
• Ability to define coding standards and lead technical discussions.
• English level B2+.
• Availability for Incident Response service.

Responsibilities

• API Design & Partner Integration: Facilitating seamless onboarding of external partners by designing robust API contracts, writing high-quality developer documentation, and creating mock environments.
• Frontend Development: Driving the development of modern web interfaces (including checkout paths, landing pages, and discovery hubs) that consume the integrated partner services.
• Technical Leadership: Bridging Java backend design with modern frontend development to ensure cohesive, end-to-end technical implementation.

Skills

Java

Kotlin

API design

OpenAPI/Swagger

RESTful APIs

JavaScript/TypeScript

React

Distributed systems

Integration patterns

OAuth 2.0

OpenID Connect

Leadership

English B2+

Incident Response

AI tooling

Security standards

Job description

The Codest, an international tech software company with a footprint in Poland, is seeking an Engineer to lead API design and partner integrations for a major European e-commerce client. You will drive frontend development (checkout paths, landing pages) using JavaScript/TypeScript and React, while bridging Java backend and frontend efforts and shaping API contracts.

Ideal candidates have strong Java/Kotlin experience, OpenAPI/Swagger know-how, and a pragmatic approach to security and scalable