Senior Backend Engineer – C#/Python – London

Senior Backend Engineer | AI x FinTech | London | £80k + Equity + Unlimited Holiday

Oliver Bernard have recently partnered with a fast-moving AI fintech start-up that’s building an AI-native product from the ground up. They’re now looking for a Senior Backend Engineer to join their early engineering team.

This is an opportunity to get in early, work directly with the founders and take real ownership of the technology.

What you’ll own

• Design, build and own core backend services, APIs and infrastructure
• Take LLM and agentic workflows from concept into production
• Own data models, failure modes, auditability and performance
• Build API-first systems and infrastructure
• Jump into React / Frontend when needed to get a feature shipped
• Work directly with the founders and help shape the technical roadmap

What they’re looking for

• 3-4+ years shipping and owning backend systems
• Experience with AI tooling, LLMs or agentic workflows
• Fintech experience is essential – payments, banking, open finance, ledgers or financial infrastructure particularly relevant
• Comfortable operating across the stack when needed
• Someone who thrives in high-agency, fast-paced environments

This is an early team hire, so you’ll have a level of ownership and influence that’s difficult to find in a larger organisation.

You’ll be close to the founders, have a direct impact on the product and get the chance to work at the intersection of AI + financial technology.

London, 3-4 days in office

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