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Description
Haystack is working with an employer on this opportunity!
Backend Engineer – Fintech Scale-Up
💰 £70,000–£90,000
📍 London (Options for full remote working or hybrid working in the London office)
🕓 Full-time | Permanent
About the Company
We’re partnered with a high-growth fintech scale-up building modern financial infrastructure that’s changing how people and businesses move money globally. Their platform powers real-time payments, automated compliance, and intelligent financial workflows used by leading UK and international clients.
They’re now looking for a Backend Engineer to help design, build, and scale systems that sit at the heart of their platform — from secure transaction processing to high-availability APIs serving thousands of requests per second.
You’ll join a small, talented engineering team working in a fast-moving environment where new ideas are encouraged, ownership is expected, and your impact will be visible from day one.
The Role
You’ll play a key role in designing and maintaining backend systems that keep mission-critical financial data flowing smoothly and securely. The ideal candidate loves solving complex problems, writing clean, testable code, and collaborating across teams to ship production-ready features.
What You’ll Do
Design, build, and maintain distributed backend systems and APIs for payment processing, data exchange, and reporting.
Collaborate with product, data, and DevOps teams to deliver new features end-to-end.
Ensure performance, reliability, and scalability across core platform services.
Implement best practices around testing, observability, and security in production.
Participate in code reviews, technical discussions, and architecture decisions.
Contribute to the continual evolution of the company’s engineering standards and culture.
Tech Stack
Languages: Node.js (TypeScript)
Frameworks: FastAPI, Express, or similar
Databases: MongoDB
Cloud: AWS (Lambda, ECS, S3, RDS), Docker
Tooling: GitHub, Terraform, CI/CD pipelines
Bonus: Experience with financial APIs, Kafka, or event-driven systems
About You
3+ years of backend development experience in production environments.
Strong understanding of API design, data modelling, and microservice architecture.
Experience building systems that handle sensitive data or high transaction volumes.
Familiarity with cloud-native development and CI/CD pipelines.
Comfortable in a fast-paced environment, balancing technical depth with delivery.
Passionate about clean code, security, and reliability.
Why Join
Work on cutting-edge fintech systems that power real-world transactions.
Join a collaborative, ambitious team where your voice genuinely counts.
Hybrid working model with flexibility around your schedule.
Competitive salary and benefits, with opportunities for progression.
A modern engineering culture focused on autonomy, quality, and impact.
💡 This is an opportunity to help shape the backend systems of one of the UK’s most exciting fintech scale-ups — where technical ownership meets tangible product impact.
Role tech stack
Node.js
MongoDB
AWS
