Senior Backend Engineer - AI FinTech, High Ownership

Oliver Bernard; Greater London; On-site; GBP 48,000 - 80,000; Full time

Job summary

Oliver Bernard is recruiting a Senior Backend Engineer for an early-stage AI fintech startup in London. You will own core backend services, APIs and infrastructure from day one, shaping an API-first platform with event-driven, multi-tenant design.

You will collaborate directly with founders and tackle LLM-driven workflows while maintaining high performance and auditable data models. This is a high-ownership role requiring 3–4+ years in backend engineering, with strong C# and/or Python skills.

Qualifications

• 3–4+ years building, shipping and owning backend systems.
• Experience with AI tooling / LLMs / agentic systems.
• Fintech experience essential across payments, banking, open finance or similar infrastructure.
• React experience is a bonus.

Responsibilities

• Design, build and own core backend services, APIs and infrastructure.
• Build event-driven, multi-tenant systems from the ground up.
• Ship LLM and agentic workflows into production.
• Own data models, failure modes, auditability and system performance.
• Build API-first products and infrastructure.
• Collaborate with founders and influence technical direction.
• Be comfortable contributing to frontend when needed.

Skills

Backend development

C#

Python

AI/LLMs

Fintech

Job description

Oliver Bernard is recruiting a Senior Backend Engineer for an early-stage AI fintech startup in London. You will own core backend services, APIs and infrastructure from day one, shaping an API-first platform with event-driven, multi-tenant design.

You will collaborate directly with founders and tackle LLM-driven workflows while maintaining high performance and auditable data models. This is a high-ownership role requiring 3–4+ years in backend engineering, with strong C# and/or Python skills.