Full Stack Engineer (AI Native)

Harnham; Greater London; On-site; GBP 77,000 - 94,000; Full time

Benefits offered by this job

Competitive salary

Comprehensive benefits package

Job summary

Harnham is seeking an Engineer to own software across front-end and back-end within an AI-first fintech environment. You will build customer-facing web applications and contribute to Kotlin/Spring backend services while integrating AI-driven workflows.

Join a scale-up with Agile squads, delivering secure, scalable software and collaborating on APIs, microservices, and event-driven architectures. Salary up to £85,000 with comprehensive benefits.

Qualifications

• Experience with Java and Kotlin backend development on the Spring stack.
• Experience with AI-assisted development, particularly using Claude or similar tools.
• Experience with CI/CD pipelines, automated testing and API integrations.
• Familiarity with Jira, Agile methodologies and collaborative software delivery.

Responsibilities

• Build and enhance customer-facing web applications.
• Contribute to backend services built with Kotlin and Spring.
• Leverage AI tools and agentic development workflows in daily engineering tasks.
• Work within Agile Scrum teams to plan, develop, test and release software.
• Collaborate on APIs, microservices and event-driven architectures.
• Drive software quality, performance, security and scalability.

Skills

Java backend development

Kotlin backend development

AI-assisted development

CI/CD pipelines

Agile methodologies

API integration

Tools

Kotlin

Spring Framework

Claude AI

CI/CD tooling

Job description

This is a great opportunity to join a high-growth fintech scale-up where you can take ownership of customer-facing products whilst working in an AI-first engineering environment. You'll help build technology that combines financial data, analytics, and behavioural insights to deliver meaningful outcomes for end users.

THE COMPANY:

This rapidly growing WealthTech business is transforming how individuals engage with their financial lives through innovative technology, sophisticated analytics, and exceptional user experience. Backed by leading investors and operating in a scale-up environment, the business is building a platform that provides users with a complete view of their financial world alongside personalised insights and recommendations.

The engineering function operates through cross-functional Agile squads and is heavily focused on leveraging AI to increase engineering productivity and innovation.

THE ROLE:

You will take ownership of software within one of the engineering squads, contributing across both front-end and back-end development while working alongside product, engineering, and technical operations teams.

Key responsibilities include:

• Building and enhancing customer-facing web applications.
• Contributing to backend services built with Kotlin and Spring.
• Leveraging AI tools and agentic development workflows as part of your day-to-day engineering process.
• Working within Agile Scrum teams to plan, develop, test and release software.
• Collaborating on APIs, microservices and event-driven architectures.
• Driving software quality, performance, security and scalability.

YOUR SKILLS AND EXPERIENCE:

You will bring strong capability in:

• Java and Kotlin backend development on the Spring stack.
• AI-assisted development, particularly using Claude and agentic engineering workflows.
• CI/CD pipelines, automated testing and API integrations.
• Jira, Agile methodologies and collaborative software delivery.

THE BENEFITS:

You will receive a salary of up to £85,000 depending on experience, along with a comprehensive benefits package.

PLEASE NOTE:

Sponsorship is not available for this position.