Principal Backend Engineer: Scale High-Volume FinTech

SR2 | Socially Responsible Recruitment | Certified B Corporation™; Greater London; On-site; GBP 120,000 - 165,000; Full time

Job summary

SR2 | Socially Responsible Recruitment | Certified B Corporation™ is seeking a Principal Backend Engineer to lead the architectural evolution of a high-growth FinTech backend platform. This role is deeply technical and hands-on, demanding strong judgment to raise engineering standards and build scalable systems.

You'll own the backend direction, design high-scale services, implement robust APIs, ensure reliability with observability, and mentor engineers while leveraging AI-assisted tooling to

Qualifications

• Deep experience with NestJS, Node.js and TypeScript.
• Strong AWS and Docker experience.
• Experience designing high-scale backend and data systems.
• Excellent API and systems architecture skills.
• Strong understanding of distributed/event-driven systems.
• Experience with relational databases such as MySQL.
• Strong understanding of reliability, observability and failure modes.
• Ability to influence technical direction without formal people management.
• Excellent engineering judgement and pragmatic decisions.
• An AI-native mindset and interest in using AI to increase engineering leverage.

Responsibilities

• Own the technical direction and architecture of the backend platform
• Design scalable systems capable of handling millions of records and events
• Establish clear boundaries between application, data and delivery layers
• Build robust, well-typed APIs and processing workflows
• Improve reliability through idempotency, retries, observability and failure isolation
• Lead technical design reviews and raise engineering standards
• Mentor engineers through code reviews and technical pairing
• Drive improvements across scalability, security and maintainability
• Use AI-assisted and agentic engineering tools to improve development, testing and technical workflows

Skills

NestJS

Node.js

TypeScript

AWS

Docker

MySQL

Event-driven architecture

Observability

Job description

SR2 | Socially Responsible Recruitment | Certified B Corporation™ is seeking a Principal Backend Engineer to lead the architectural evolution of a high-growth FinTech backend platform. This role is deeply technical and hands-on, demanding strong judgment to raise engineering standards and build scalable systems.

You'll own the backend direction, design high-scale services, implement robust APIs, ensure reliability with observability, and mentor engineers while leveraging AI-assisted tooling to