Staff Engineer - Core Markets

Department: Engineering

Location: London

Employment Type: FullTime

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.

We’re looking for a Staff Engineer to lead the technical vision and architecture for 9fin’s Core Markets engineering organisation.

In this role, you’ll define and evolve the system design that underpins our future expansion—owning the end-to-end architecture, setting technical direction, and ensuring our platforms scale effectively. You’ll create clear technical documentation, align multiple engineering teams around a shared vision, and guide execution by helping teams make thoughtful trade-offs.

This is a high-impact, hands-on leadership role on the IC track. You’ll operate across strategy and execution—partnering with 6+ teams, contributing directly to critical code paths when needed, and raising the engineering bar across the organisation.

What you'll do

• Define technical strategy and architecture across Platform, AI, Retrieval, and shared engineering services.

• Partner with Engineering Leaders and Staff Engineers to drive technical direction and platform investments.

• Design scalable backend systems, APIs, and shared platform capabilities.

• Guide architecture across teams, helping reduce complexity and establish common patterns.

• Partner with AI and Retrieval teams to build scalable search and RAG capabilities.

• Lead complex cross-team technical initiatives from design through production.

• Improve platform reliability, scalability, observability, and developer experience.

• Contribute hands-on to critical technical work and set a high engineering bar through design reviews, mentoring, and technical leadership.

• Leverage AI-assisted engineering to improve productivity and accelerate delivery.

What we're looking for

• Experience designing and building large-scale backend systems and distributed architectures.

• Strong systems design skills and experience leading cross-team technical initiatives.

• Experience with cloud infrastructure (AWS), Kubernetes, APIs, and modern backend development.

• Familiarity with AI-powered systems, Retrieval-Augmented Generation (RAG), search platforms, or vector databases.

• Strong programming experience in Python or another modern backend language.

• Comfortable influencing technical direction without direct authority.

• Excellent communication skills and a passion for mentoring engineers and raising engineering standards.

Nice to have:

• Experience as a founding engineer or CTO at a startup, or building systems from scratch in early-stage environments

• Experience modernising legacy systems.

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 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

Time off

• 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

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.