Product Engineer, Backend

9fin; Greater London; On-site; GBP 60,000 - 80,000; Full time

Benefits offered by this job

Competitive Salary

Private Medical Insurance

Pension Matching

Hybrid Working Model

Job summary

A leading AI platform company in Greater London is looking for a skilled backend developer who excels in Python and has experience with Flask and FastAPI. This role offers the opportunity to take technical leadership on diverse projects while working closely with cross-functional teams. You will be responsible for development, implementing APIs, and enhancing service functionality within a supportive hybrid work environment. Benefits include a competitive salary, professional development budget, and a flexible working model.

Qualifications

• Ability to plan and reason about software within systems and business.
• Understanding of data flow from storage to API endpoints.
• Experience with writing testable, maintainable code.

Responsibilities

• Lead technical projects and define systems.
• Implement and deliver new service functionality.
• Collaborate with cross-functional teams for project success.

Skills

Python

Flask

FastAPI

SQL

API Development

Collaboration

Tools

Docker

PostgreSQL

AWS

Job description

About 9fin

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

Overview

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.

What You’ll Work On

• This role is the opportunity to take on the technical leadership on projects, defining and designing systems, making quick proof of concepts and working closely with Product and our Clients.
• Write code and lead others in the team in delivering new service functionality, implementing API’s, data routing/processing and automation mechanisms.
• Development and engineering primarily on the backend services and web application hosted tools and systems of the 9fin platform.
• Taking a leading role within project teams as an IC, running code reviews and mentoring of junior developers, involvement in early research and experimentation with new technologies providing input for new features and products.
• Continually improve on the 9fin codebase taking the chance to automate, refactor and document when you can.
• Variety: Our web platforms are incredibly diverse, from complex financial data modelling, 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 Backend Stack

• Python is the dominant backend language used
• Flask & FastAPI
• 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’re AWS for Cloud hosted services
• Heavy use of AWS lambda Serverless
• Docker (AWS ECS) for uniform development/deployment from dev to prod

Requirements

• Can effectively plan and reason about your software, understanding where it fits into systems and the overall business
• Can think about how data will pass through your software; from persistent storage through to API endpoint
• Experience with Python and its web frameworks (we currently use Flask, and are moving to FastAPI with Typing)
• Strong experience delivering APIs, Service Oriented Architecture
• Good working knowledge of SQL statements for retrieving data
• A good collaborator and communicator with cross functional engineering teammates and others within 9fin
• Code Quality: Through writing testable, maintainable code, and by engaging in code review for your own work and for reviewing others

Company 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)
• 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

Equal Opportunities

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.