Senior Product Engineer

About 9fin

9fin is the AI platform powering global debt markets — the world’s largest asset class at over $145 trillion.

What you'll work on

• As part of a cross functional team, lead projects by defining and designing systems, building proof of concepts, and delivering new service functionality - including APIs, data processing and automation - while collaborating with Product and Clients
• Development and engineering primarily on the backend services and web application hosted tools and systems of the 9fin platform.
• Play an impactful role within project teams as a senior IC, running code reviews, mentoring other developers, leadership & involvement in early research and experimentation with new technologies providing input for new features and products.
• Continually improve the 9fin codebase taking the chance to automate, refactor and document when it’s most impactful..
• Very diverse web platforms, from complex financial data modelling, complex access control business logic, capturing environmental, emission, energy data, incorporation of ML/AI prediction services, data visualisation serving and automation systems.
• Collaboration and teamwork: Cross functional teams are formed for all projects including the appropriate domain expertise from 9fin financial, legal and editorial colleagues. This allows the best quality information and feedback to go directly to engineering project teams. Your ability to explain and break down complex projects to non technical audiences will enable productive and efficient team progress.
• Developer Experience: Through managed automated preview environments, feature flags and well maintained non production environments. You will be able to move with velocity and get feedback and iterate quickly.

Our Stack

• Python is the dominant backend language used
• Flask & FastAPI
• React & TypeScript
• Typing is used within our Python stack to power automated documentation and API definitions
• Relational Databases (PostgreSQL) at the heart of majority of services
• We have our own internal developer platform with standardised paved road approaches to infrastructure to bring your code into production as quickly as possible.
• We’re AWS for Cloud hosted services
• Heavy use of AWS lambda Serverless
• Docker (AWS ECS) for uniform development/deployment from dev to prod

Requirements

• Have experience operating as a Senior IC Engineer, leading systems design and infrastructure discussions, mentoring more junior team members, and scoping work within cross-functional product teams.
• Comfortable moving between frontend and backend work, picking the right tool for the problem rather than specializing in one area.
• Strong knowledge of modern JavaScript/TypeScript and frameworks such as React, alongside experience building scalable backend services and APIs.
• Comfortable leveraging modern AI-assisted development tools (e.g. Cursor, Claude, ChatGPT, GitHub Copilot) to improve productivity while maintaining high engineering quality.
• A strong product mindset with an eye for user experience, working closely with designers and product managers to craft intuitive, polished interfaces.
• Able to independently own features from idea through design, implementation, deployment and iteration.
• Strong system design and problem-solving skills, balancing speed with long-term maintainability.

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)
• 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

Location
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