Senior Product Engineer - Go | FinTech (D875AAA)

Referment; Greater London; Hybrid; GBP 110,000 - 150,000; Full time

Job summary

Referment is seeking a senior backend engineer to design and lead Go microservices on AWS, shaping scalable B2B API services. You will mentor engineers, drive architecture and influence hiring and strategy within a small, collaborative team.

The role is hybrid, based in London with in-office days and remote work, focusing on high performance, security and AI-assisted engineering judgements.

Qualifications

• 5+ years of commercial software engineering experience with Go.
• Experience building and operating B2B API services in production.
• Experience scaling B2B API services on AWS in a regulated environment.
• Mentoring engineers and leading code reviews.
• Sound architectural judgement and ability to evolve systems carefully.

Responsibilities

• Design and lead architecture of high-performance Go microservices on AWS.
• Mentor mid-level engineers and coach their craft.
• Lead technical delivery with quality, maintainability and security standards.
• Drive architectural decisions across services, data layer and API surface.
• Contribute to hiring, technical strategy, roadmaps and engineering culture.

Skills

Go

AWS

API services

Mentoring

CI/CD

Architectural design

Tools

Fargate

Lambda

Aurora Postgres

DynamoDB

SageMaker

Bedrock

GitHub Actions

Job description

Referment is working with a UK fintech scale-up that supplies lenders with real-time credit information and analytics through API-first products, so lending decisions draw on data that reflects consumers as they are today rather than weeks-old credit files. Its engineering team is small and collaborative, and is scaling to meet growing customer demand.

You'll take a foundational senior product engineering role, providing technical leadership as the team grows: mentoring mid-level engineers, leading code reviews and shaping the architecture of B2B API services on AWS. You'll be the senior technical voice in the team, setting the bar for code quality, design taste and delivery, and making deliberate, responsible use of modern AI tooling — AI as an assistant to engineering judgement, never a replacement for it.

The Role

• Design and lead the architecture of high-performance Go microservices on AWS, with a focus on scale, reliability, automation and security.
• Mentor mid-level engineers — pair, coach, unblock and grow their craft.
• Lead technical delivery, setting and upholding standards for quality, maintainability and security.
• Drive architectural decisions and trade-offs across services, the data layer and the API surface, with a bias to action.
• Contribute to hiring, technical strategy, roadmaps and the wider engineering culture.

What We're Looking For

• 5+ years of commercial software engineering experience, with real depth in Go and experience building and operating B2B API services in production.
• Demonstrable experience scaling B2B API services on AWS — designing for performance, availability and security in a regulated environment.
• Expertise in managed AWS platform components — Fargate, Lambda, Aurora Postgres, DynamoDB, SageMaker, CloudWatch and Bedrock — working primarily in Go alongside some Python, C and TypeScript.
• A strong grounding in modern CI/CD practices (GitHub Actions), containers and distributed systems.
• A track record of mentoring engineers and leading code review.
• Sound architectural judgement — knowing when to introduce abstraction, when to keep things simple, and how to evolve a system without big-bang rewrites.
• Fluent, deliberate use of AI development tools, with a clear-eyed view of where they help engineering excellence and where they don't.

Fintech, credit or other regulated-industry experience is a strong plus.

The role is hybrid, based in London with two to three days a week in the office and the rest working from home.

This could suit...

a senior backend engineer from a fintech or other regulated-tech background who wants foundational architectural ownership in a small team, or an engineer from a high-scale B2B API environment ready to be the technical leader a growing team builds around.

#Referment