Senior AI Platform Engineer

About 9fin 9fin is the AI platform powering global debt markets — the world’s largest asset class at over $145 trillion. Debt markets are vast, global, and mission-critical, yet still run on fragmented data, PDFs, and manual workflows. 9fin replaces this broken infrastructure with a single platform that centralises proprietary credit data, deep analysis, and high-value workflows across global markets. Today, 9fin powers teams at 300+ blue-chip institutions worldwide, including global banks, asset managers, private equity firms, law firms, and advisors. The business is scaling at exceptional speed, with rapid expansion in the US and best-in-class retention driven by deep workflow adoption. We’re at a defining inflection point. With proven product-market fit and strong, global market pull, 9fin is accelerating toward becoming the category-defining platform for debt markets worldwide. The Opportunity Debt is a $145 trillion market that still runs on PDFs and spreadsheets. 9fin is changing that: AI-powered intelligence that gives 300+ banks, asset managers, PE firms and law firms the answer in minutes, not days. We’ve just closed our Series C, and AI is at the heart of what we build next. We’re looking for a Senior AI Platform Engineer to build the foundation beneath it. This is greenfield: a V1 exists, but the big decisions are still ahead. You’ll design the core platform behind Generative AI, Agentic AI and ML at 9fin: one home for every agent, delivering “AI as a service” to a dozen or more teams. Your work will power everything from document understanding to autonomous agents that run scheduled workflows, write morning briefings and flag distressed companies. What You’ll Work On No two weeks look the same, but you can expect to: Build the platform behind our agents: agent runtime and orchestration, model serving, sandboxing, and tracing and evals Create shared components: prompt management, AI gateways and evaluation services Ship APIs, SDKs and tooling so teams can launch agents without rebuilding infrastructure Design secure, scalable deployment pipelines for models and applications Build observability: tracing, evaluation, cost and quality in production Set standards for testing, governance, Responsible AI and operations, and keep evolving the platform as the ecosystem moves What Makes This Role Different Build, don’t maintain. Many architectural decisions are still open, and they’re yours to shape. A real roadmap. Memory, artifacts and event-driven agents come first. Within six months, you’ll help ship agents that run autonomously in the background. A top 2027 bet. Agent orchestration is a strategic priority, and you’ll help drive it, towards a 9fin experienced through agents. Leverage. You’ll build shared capabilities that let multiple teams ship AI at scale, rather than owning a single product. Real influence. You’ll be one of a small group of senior engineers shaping direction alongside the Engineering Lead. No management duties required. About You You’ll be a great fit if you are an engineer who has built real AI systems in production, cares about developer experience, and wants to own something from the ground up. AI Platform Engineering 5+ years of software engineering experience, including 2+ years building AI/ML platforms, Generative AI applications or production machine learning systems Experience designing and deploying enterprise AI applications to production, with a focus on scalability, reliability and developer experience LLMs & Agentic AI Hands-on experience building applications powered by Large Language Models Experience building Model Context Protocol (MCP) and Retrieval-Augmented Generation (RAG) solutions, using embeddings, vector databases and modern LLM orchestration frameworks Experience building or contributing to agentic AI systems, intelligent workflows or orchestration frameworks Backend & Platform Engineering Strong backend engineering with production experience in Python and/or TypeScript Experience designing scalable backend services and REST APIsExperience building reusable platform capabilities, internal developer tooling, SDKs or shared engineering services Cloud & Infrastructure Strong experience building cloud-native applications Comfortable with Docker, Kubernetes, CI/CD pipelines and containerised deployments Experience with solutions such as AWS Bedrock and AgentCore Understanding of how to deploy, monitor and operate AI services in production AI Operations & Observability Experience implementing monitoring, tracing, evaluation and cost optimisation for AI systems Experience with observability tools such as Langfuse, Arize Phoenix, or Langsmith Understanding of the operational challenges of LLM-powered applications, including latency, reliability, hallucination monitoring and model quality evaluation Collaboration & Technical Leadership You enjoy working across engineering disciplines to shape technical direction and set best practice You are comfortable being one of a small group of senior engineers, influencing architecture and platform direction without needing formal management responsibility You thrive in fast-moving environments where much is still being designed and built You have driven projects rather than just contributed to them, and can explain the impact of what you built Bonus Points Experience with any of the following will help: AI gateways and model routing Prompt management platforms AI evaluation frameworks LangGraph, LangChain, LlamaIndex, DSPy, CrewAI or similar orchestration frameworks Vector databases and semantic retrieval Knowledge graphs or document understanding systems Building internal AI platforms used by multiple engineering teams Benefits We’re a scaling start up, and we enjoy sharing our success, when the company succeeds, we always reinvest that in our people. We also offer huge amounts of responsibility, an abundance of opportunity for growth and a platform to truly excel. Financial & Insurance Competitive Salary (our salary bands are benchmarked at the top end of the market) Equity Pension (your minimum contributions are 4% with 9fin matching up to 7%) Private Medical Insurance Paid sick leave with Income Protection for long periods of illness Group Life Assurance Season Ticket Loan & Cycle to Work schemes Time off 25 holiday days per year Local public holidays (with the ability to exchange them for alternative days) Work abroad for up to 3 months a year 1 month paid sabbatical after 5 years of service Enhanced parental leave & flexible working arrangements available Training & Culture Professional learning and development budget AI experimentation budget of £800 (UK) per employee to trial AI tools Quarterly team socials Summer and Winter company social events Hybrid Policy 9fin is a hybrid company, and the office is a regular part of how we work. From January 2027, all employees will work from their designated 9fin office on Tuesdays and Wednesdays. Some teams may be asked to be in the office more often, where the nature of their work calls for it. For the rest of the week, you may work from wherever works best for you and your team. Your Talent Partner will share hybrid working details for this role. 9fin is an equal opportunities employer At 9fin we are dedicated to building and promoting a fair and inclusive workplace where everyone can reach their full potential and truly belong. We recognize that building diverse teams enables a more creative and productive environment. If you’re excited about this role but your experience doesn’t perfectly align with the job description, we encourage you to apply anyway. You might just be who we’re looking for — either for this role, or perhaps another.