cover image
9fin

Full Stack Engineer

Hybrid

London, United kingdom

Full Time

04-03-2026

Share this job:

Skills

Teamwork Python SQL PostgreSQL Docker AWS Lambda Research Architecture Databases AWS Flask FastAPI

Job Specifications

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.

What You’ll Work On

As part of a cross-functional team, contribute to projects by helping design systems, building proof of concepts, and delivering new service functionality — including APIs, data processing, and automation — while collaborating closely with Product and Clients.
Development and engineering primarily on backend services and web-application–hosted tools and systems within the 9fin platform.
Play an impactful role within project teams as an individual contributor, participating in code reviews, collaborating with peers, and contributing ideas during research and experimentation with new technologies.
Continually improve the 9fin codebase by taking opportunities to automate, refactor, and document where it’s most valuable.
Work across a diverse set of web platforms, including financial data modelling, access-control business logic, environmental and emissions data capture, integration with ML/AI prediction services, data visualisation, and automation systems.
Collaboration and teamwork: All projects are delivered by cross-functional teams that include domain expertise from 9fin’s financial, legal, and editorial colleagues. You’ll work closely with non-technical stakeholders and help explain technical concepts in a clear, accessible way to support effective team progress.
Developer experience: You’ll work within a strong developer experience setup, including automated preview environments, feature flags, and well-maintained non-production environments, enabling rapid iteration and feedback.

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 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

This role will be a great fit if you:

Have experience working as a Full-Stack or Backend-leaning Engineer within a product team, contributing to system design discussions and delivering production software.
Can plan and reason about software effectively, clearly communicating how your work fits into larger systems and delivers value to clients.
Have hands-on experience designing and implementing data flow through software, from persistent storage to API endpoints, applying industry best practices for validation and reliability.
Have experience with Python and web frameworks (we currently use FastAPI with strong typing and Pydantic).
Have experience building and consuming APIs, ideally within a service-oriented architecture.
Have a working knowledge of SQL for querying and working with relational data.
Are a collaborative and proactive communicator, comfortable working with engineers and non-engineers across the business.
Care about code quality, writing testable and maintainable code, and actively participating in code reviews — both receiving feedback and reviewing others’ work.

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
Enha

About the Company

9fin is the faster, smarter way to find debt market intelligence. Through an AI-powered data and analytics platform, 9fin centralises everything that's needed to analyse a credit or win a mandate in one place - helping subscribers win business, outperform their peers and save time. Know more