Fintech Full-Stack Engineer: AI-Driven Platform Builder

FLEX FUNDING A/S; København; On-site; DKK 800,000 - 1,000,000; Full time

Benefits offered by this job

Live fintech platform with real value

Small, trusted team

Ownership over architecture and AI

Modernisation of an established system

Nordics expansion

Job summary

FLEX FUNDING A/S in Copenhagen is seeking a skilled full-stack developer to join a two-person team responsible for a broad fintech platform. You will make technical decisions, collaborate with an external DevOps partner, and work closely with product, business, compliance, and external partners.

The role emphasizes AI-enabled development, end-to-end delivery, and modernization of a monolith while maintaining production systems and security.”

Qualifications

• Strong full-stack fundamentals with ability to explain technical choices.
• Fluent use of AI tools in development workflow.
• Ability to review and validate AI-generated code.
• Ownership beyond implementation and maintainability.
• Comfort across frontend, backend, databases and integrations.
• Proactive in seeking clarifications and driving progress.
• Willingness to learn unfamiliar parts of the platform.
• Clear communication with technical and non-technical colleagues.

Responsibilities

• Build end-to-end solutions from idea to production-used systems.
• Modernise an existing monolithic platform for better structure and features.
• Apply AI across development, testing, documentation, and refactoring.
• Own reliability, security, performance, and maintainability of solutions.
• Work with financial workflows and third-party integrations.

Skills

Full stack engineering

AI-assisted development

Code review

Ownership

Frontend development

Backend development

Databases

Integrations

Proactive communication

Clear collaboration

Tools

TypeScript

Vue / Nuxt

.NET / C#

Azure

CI/CD

SQL

Job description

FLEX FUNDING A/S in Copenhagen is seeking a skilled full-stack developer to join a two-person team responsible for a broad fintech platform. You will make technical decisions, collaborate with an external DevOps partner, and work closely with product, business, compliance, and external partners.

The role emphasizes AI-enabled development, end-to-end delivery, and modernization of a monolith while maintaining production systems and security.”