Senior Backend Engineer (Fynn, AI Credit Coach)

Join Kikoff, a consumer fintech startup, as a Senior Backend Engineer. You will work with experienced entrepreneurs and have a direct impact on customers' financial well-being. Your responsibilities will include designing and implementing core backend systems, building LLM-powered workflows, and enhancing observability and reliability. You will collaborate with product, data science, and operations teams to deliver features that improve customers' financial lives.

• Design and implement the core backend systems behind Fynn, including the conversational AI layer, personalization engine, and orchestration that connects users to Kikoff's suite of tools.
• Build LLM-powered workflows and agents, integrating model providers, retrieval over user credit and financial data, tool-calling, and the AI Debt Negotiation voice agent into reliable, production-grade pipelines.
• Own the evaluation and quality infrastructure that lets us ship safely, including automated scorers across accuracy, tone, compliance, and privacy, plus the tooling to test prompt and model changes before they reach users.
• Solid understanding of database optimization, caching strategies, and performance tuning
• Track record of making infrastructure decisions that balance technical excellence with business pragmatism
• Production experience with background job processing systems (Sidekiq, Resque, or similar)
• Comfort building in an environment where correctness, latency, and user trust all matter at once
• 5+ years of experience with modern backend frameworks and a track record of building and scaling production systems
• Strong systems design skills; you've architected and shipped distributed systems that handle high throughput and maintain data consistency
• Hands-on experience building LLM-powered products such as RAG, agentic/tool-calling workflows, prompt engineering, or eval frameworks
• Experience working within a client-server architecture, even if only on one side of it (backend services, the client/mobile app, or the API contract between them)
• Experience with AI quality and safety systems: automated evaluation, guardrails, and testing model/prompt changes before release
• Experience with payment systems, financial infrastructure, or regulated environments (ACH, card processing, credit bureau data)
• Background in fintech, payments, or lending infrastructure
• Technical Leadership: Ability to own complex technical initiatives end-to-end, from design through implementation and rollout
• Mentorship: Help level up the team through code reviews, design docs, and technical guidance
• Impact Focus: Balance technical perfection with pragmatic delivery; you know when to build for scale vs. ship fast
• Cross-functional Collaboration: Partner effectively with product, data science, and operations to deliver customer value
• Operational Excellence: Take ownership of the reliability and performance of the systems you build