Full-Stack API Developer

Quick Facts

• 100% remote work (with onboarding and occasional on-site visits)

• Languages: German + English

• Start: ASAP / within 2 weeks

• B2B contracting, up to 45 EUR/h

• Duration: first contract until the end of the year, then regular 6–12 month extensions

• Onboarding: 1 week on-site in Hanover; additional visits once every 2–3 months for ~3 days on demand

• Workload: full-time (40 hours/week)

• Industry: Finance

Description

The Full-Stack API Developer integrates REST APIs into existing systems, enhancing workflows and supporting clients with technical integration. You will deliver full-stack development across the JavaScript ecosystem (frontend & backend) and translate business requirements into technical solutions within a distributed agile team. The role also includes analyzing the existing codebase and contributing to architectural decisions.

Responsibilities

• Develop and integrate REST API interfaces into existing systems

• Implement technical requirements within a large-scale integration and brokerage project

• Perform full-stack development in the JavaScript ecosystem (frontend & backend)

• Collaborate with internal and external developers in a distributed agile setup

• Analyze and evaluate the existing codebase; contribute to architectural decisions

• Convert business requirements into technical solutions and maintain documentation

• Work closely with team leads, business units, and stakeholders

• Support onboarding-related topics (firewall, whitelisting, internal processes; client provides guidance)

Requirements

• Strong experience in Java, REST API development, and API design

• Excellent JavaScript skills (full-stack)

• Proven experience as a Full-Stack Developer

• Background in agile software development

• Ability to analyze, structure, and optimize existing code

• Proactive communication and team collaboration

• Fluent German (B2+/C1) for documentation and daily communication

Benefits

• 100% remote work model with onboarding and periodic on-site visits

• B2B assignment with hourly compensation (up to 45 EUR/h)

• Expected contract extensions after the initial term