9fin - Principal Engineer
Requirements
• You're the person who: • Has operated at principal or staff level in a data-intensive, fast-moving engineering org — and has the range to show for it • Can credibly walk into a conversation about data pipeline architecture, RAG evaluation, API design, or system scalability — and add something useful in all of them • Owns problems, not just opinions. You're not here to review and advise; you're here to make calls and be accountable for them • Writes code when it matters — the proof of concept that validates a direction, the deep dive that unblocks the team, the PR that sets the standard others build from • Has strong opinions about what good engineering looks like and can defend them without being precious about being wrong • Is energised by the problems nobody else can solve, not unsettled by them • Deep experience with complex data modelling, entity resolution, and data pipelines in production environments • Proven experience designing and shipping AI/LLM systems — RAG, structured extraction, evaluation frameworks — beyond the prototype stage • Strong backend and distributed systems knowledge: APIs, service architecture, scalability, observability • Experience making and owning foundational architectural decisions that affected how an entire engineering org worked • Proficiency in Python; comfort across the stack where it matters • Experience with financial data, legal documents, or other semi-structured, domain-rich datasets • Background as a founding engineer, early-stage CTO, or technical lead who has built systems from scratch and lived with the consequences
Benefits
• The problems you'll own are genuinely hard — messy financial data, complex entity relationships, AI systems where correctness really matters • You'll have real authority over foundational decisions, not just influence over them • 9fin's engineering org is strong and growing — you'll be working with and stretching great engineers, not compensating for weak ones • High ownership, high impact, and the chance to shape how a serious data and AI company scales its technical foundations • 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 options • 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 • 25 holiday days per year • Local public holidays (with the ability to exchange them for alternative days) • Hybrid working model, to allow you the flexibility to decide how, where and when you do your best work • 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 • Quarterly team socials • Summer and Winter company social events • 9fin is an equal opportunities employer
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