Senior Full-Stack Engineer (with AI agents experience)

N-iX; España; Híbrido; EUR 90.000 - 130.000; Jornada completa

Ventajas ofrecidas por este puesto de trabajo

Flexible working format

Competitive salary

Career growth

Mentorship program

Tech talks and trainings

Centers of excellence

Knowledge sharing

Education reimbursement

Team events

Descripción de la vacante

N-iX is recruiting a Senior Full-Stack Engineer to work on Kotlin backend and React/TypeScript frontend, with a strong preference for frontend or backend depth and the ability to move across layers to unblock delivery.

Join a European fintech client with AWS-first architecture and cross-functional squads, delivering AI-native practices across the CDLC and driving scalable software in a dynamic environment.

Formación

• Kotlin backend and React/TypeScript frontend experience.
• AI-native delivery practices across the CDLC.
• Ability to move across stack layers with ease.
• Experience with AWS cloud services.
• Evidence of building/operating agent and harness tooling.

Responsabilidades

• Deliver across the Kotlin backend and React/TypeScript frontend.
• Move fluidly between stack layers to unblock delivery.
• Apply AI-native delivery practices across the CDLC.
• Multiply the output and quality of the squad and share patterns.
• Embed directly into a client squad as an individual contributor.

Conocimientos

Kotlin backend

React TypeScript frontend

AI-native delivery

Cross-stack fluency

AWS experience

Agent & harness tooling

Descripción del empleo

N-iX is a global software development service company that helps businesses across the globe create next-generation software products. Founded in 2002, we unite 2,400+ tech-savvy professionals across 40+ countries, working on impactful projects for industry leaders and Fortune 500 companies. Our expertise spans cloud, data, AI/ML, embedded software, IoT, and more, driving digital transformation across finance, manufacturing, telecom, healthcare, and other industries. Join N-iX and become part of a team where your ideas make a real impact.

About the Client

Our client is a fast-growing European fintech company in the business spend management space — corporate cards and related financial products — serving SME and mid-sized business customers across the EU and UK, in a regulated environment with GDPR compliance obligations. Engineering is organized into cross-functional squads, with platform/enabling teams providing shared tooling horizontally. The client already runs an AI-native engineering practice: Claude Code and GitHub Copilot are used daily, supported by a growing library of shared, versioned Skills embedded in key repositories, enabling an end-to-end flow from ticket to implementation, testing and PR in several codebases. AI tool/connector rollout follows an approved-list and pilot process. The client is AWS-first overall; for data platform and analytics workloads it also runs GCP, with BigQuery as the primary data warehouse. Day-to-day coordination is Slack-first, with Linear for ticket tracking, GitHub for code/PR review, and Notion as the knowledge base.

About the Role

We're looking for a Senior Full-Stack Engineer working across the Kotlin backend and React/TypeScript frontend, with a clear leaning toward either front-end or back-end depth and the ability to move fluidly between layers to unblock delivery.

Key Responsibilities

• Deliver across the Kotlin backend and React/TypeScript frontend
• Move fluidly between stack layers to unblock delivery
• Apply AI-native delivery practices across the CDLC
• Multiply the output and quality of the squad you join, and share patterns/practice beyond your immediate team so adoption compounds across the organisation
• Embed directly into a client squad as a hands-on Individual Contributor (not a coaching/managerial role).

Must-Have Skills

• Kotlin (backend) and React/TypeScript (frontend)
• AI-native delivery practices applied across the CDLC
• A clear leaning toward front-end or back-end depth, with the ability to move fluidly across stack layers
• Experience with AWS
• Agent & harness engineering fluency, with concrete evidence of building/operating this kind of tooling, not just using it.

Nice-to-Have Skills

• PostgreSQL

We offer*

• Flexible working format - remote, office-based or flexible
• A competitive salary and good compensation package
• Personalized career growth
• Professional development tools (mentorship program, tech talks and trainings, centers of excellence, and more)
• Active tech communities with regular knowledge sharing
• Education reimbursement
• Memorable anniversary presents
• Corporate events and team buildings
• Other location-specific benefits
• not applicable for freelancers