Full-Stack Engineer - Hybrid, API & Data Platform Focus

9fin; Greater London; Hybrid; GBP 75,000 - 115,000; Full time

Benefits offered by this job

Competitive salary

Pension

Private medical insurance

Sick leave

Life assurance

Season ticket loan

Cycle to work

Hybrid working

Work abroad for up to 3 months

Sabbatical after 5 years

Job summary

9fin is the AI platform powering global debt markets. A Backend/Full-stack engineer is sought to design systems, build APIs, and advance data processing within our Python stack (FastAPI/Flask) on a hybrid UK-based team.

You will develop backend services, contribute to a broad range of platforms and collaborate with cross-functional teams, including product and clients, to deliver new features and improve the codebase with automation and testing.

Qualifications

• Experience as a full-stack or backend-focused engineer in a product team.
• Ability to plan and reason about software within larger systems.
• Experience designing data flow from storage to API endpoints with validation.
• Proficiency with Python and web frameworks (FastAPI with typing and Pydantic).
• Experience building and consuming APIs, ideally in a service-oriented architecture.
• Working knowledge of SQL for relational data.
• Collaborative and proactive communicator with engineers and non-engineers.

Responsibilities

• Contribute to projects by helping design systems, build proof of concepts, and deliver new service functionality (APIs, data processing, automation).
• Develop and maintain backend services and web-application–hosted tools within the 9fin platform.
• Participate in code reviews and collaborate with peers on new ideas and technologies.
• Improve the codebase through automation, refactoring, and documentation.
• Work across financial data modelling, access-control logic, data capture, ML/AI integration, visualization, and automation.
• Collaborate with cross-functional teams including financial, legal, and editorial colleagues to explain technical concepts.
• Support rapid iteration with strong developer experience practices (preview environments, feature flags, non-production environments).

Skills

Backend engineering

Full-stack

API design

Data flow

Communication

Tools

Python

Flask

FastAPI

PostgreSQL

Docker

AWS

ECS

Job description

9fin is the AI platform powering global debt markets. A Backend/Full-stack engineer is sought to design systems, build APIs, and advance data processing within our Python stack (FastAPI/Flask) on a hybrid UK-based team.

You will develop backend services, contribute to a broad range of platforms and collaborate with cross-functional teams, including product and clients, to deliver new features and improve the codebase with automation and testing.