Senior Backend Engineer

This is a job that Jill, our AI Recruiter, is recruiting for on behalf of one of our customers. She will pick the best candidates from Jack's network. The next step is to speak to Jack. Job Title Senior Backend Engineer Salary £65k–£95k + Equity Company Description Dolfin is a Balderton-backed fintech building the first agentic financial ops API for SMB platforms. Part of the Balderton Launched program, Dolfin enables banks and vertical SaaS to embed AI-native agents for invoicing and expenses. With a unicorn client already signed and a multi-million pound pipeline, they are leading the shift from copilots to autonomous finance. Job Description Join the founding team at Dolfin to build the core infrastructure for AI-native financial operations. You will design and ship event-driven, multi-tenant systems that power autonomous agents for real-world SMBs. This is a deep, hands-on build role focused on reliability and correctness in a high-stakes fintech environment where performance and auditability are non-negotiable. Location London, UK Why this role is remarkable Build production-ready AI agents rather than simple demos, shipping real LLM-driven workflows that manage mission-critical operations for enterprise-scale platforms.Join an elite early-stage team part of Balderton’s Launched program, working directly with founders to shape the technical architecture and culture from the ground up.Tackle deep backend challenges in a high-growth category, with the autonomy to own significant surface area and make high-impact technical decisions from day one. What You Will Do Design and own core backend services, APIs, and event-driven infrastructure that partners embed directly into their vertical SaaS or banking products.Implement complex state machines and data models that ensure absolute correctness and auditability for financial processes like invoicing, bills, and automated expenses.Partner with the founders to navigate technical trade-offs, scaling the platform to handle multi-million pound pipelines while maintaining high reliability and performance. The ideal candidate Has 4+ years of experience shipping production-grade backend systems, with an essential background in fintech API infrastructure like payments, ledgers, or open finance.Demonstrates deep expertise in building multi-tenant, event-driven architectures and a high degree of autonomy to solve ambiguous problems without extensive hand-holding.Possesses a product-minded approach, comfortable moving across the stack when necessary and prioritizing pragmatic, reliable technology choices to solve real-world financial operation problems. Who are Jack & Jill? Ok, I'll go first. I'm Jack, an AI that gets to know you on a quick call, learning what you're great at and what you want from your career. Then I help you land your dream job by finding unmissable opportunities as they come up, supporting you with applications, interview prep, and moral support. And I'm Jill, an AI Recruiter who talks to companies to understand who they're looking to hire. Then I recruit from Jack's network, making an introduction when I spot an excellent candidate. How does this work? Jack's an AI agent for job searching and career coaching. He works for you.Jill is the AI recruiter working for the company. She recruits from Jack's network.If it's a match and the company wants to meet you, they'll make the intro. In the meantime, if you'd like, Jack will send you excellent alternatives. We never post fake jobs This isn't a trick. This is an open role that Jill is currently recruiting for from Jack's network. Sometimes Jill's clients ask her to anonymize their jobs when she advertises them, which means she can't share all the details in the job description. We appreciate this can make them look a bit suspect, but there isn't much we can do about it. Give Jack a spin! You could land this role. If not, most people find him incredibly helpful with their job search, and we're giving his services away for free.