Senior & Lead Backend Engineer (Python)

November 3, 2026

Hybrid

Senior

London Area, United Kingdom

Also worth knowing

Mandatory office attendance

Description

A fast-scaling AI B2B FinTech backed by Series C funding is hiring a Senior or Lead Backend Engineer on the IC track to own technical strategy and architecture across multiple engineering teams. The role covers large-scale distributed systems, scalable APIs, reliability, scalability and observability, working closely with AI and Retrieval teams on search, RAG and data-intensive systems. The engineer stays hands-on while setting engineering standards, leading cross-team initiatives and mentoring other engineers

Responsibilities

Designing and evolving large-scale backend and distributed systems
Defining technical strategy across Platform, AI, Retrieval and shared engineering services
Designing scalable APIs and shared platform capabilities
Leading complex, cross-team technical initiatives from design through to production
Improving reliability, scalability, observability and developer experience
Working closely with AI and Retrieval teams across search, RAG and data-intensive systems
Reducing architectural complexity and establishing common engineering patterns
Contributing hands-on to critical technical work while raising standards through design reviews and mentoring
Using AI-assisted engineering to improve productivity and accelerate delivery

Requirements

Strong experience designing and building large-scale backend systems and distributed architectures
Excellent systems design skills, with evidence of making significant architectural decisions
Experience leading technically complex initiatives across multiple engineering teams
Strong backend programming experience with Python or another modern backend language
Strong experience with AWS, Kubernetes, APIs and modern cloud infrastructure
Comfortable influencing engineering strategy without direct authority
Able to move between high-level technical strategy and hands-on engineering
Strong communication skills with experience mentoring engineers and raising engineering standards
Comfortable making pragmatic technical trade-offs in complex, scaling environments
Experience with AI-powered systems, RAG, search platforms, retrieval systems or vector databases would be particularly valuable
Experience as a Founding Engineer or CTO, building systems from scratch in an early-stage environment, or modernising complex legacy systems would be highly relevant