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Senior Backend Engineer

9fin· Engineering
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LondonFull-timePosted 3w ago

About the role

Senior IC Backend Engineer responsible for designing systems, building APIs and data processing, mentoring teammates, and delivering new service functionality within 9fin's backend stack.

Responsibilities

  • 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
  • Work with very diverse web platforms, including financial data modelling, access control logic, environmental/energy data capture, ML/AI prediction services, data visualisation, and automation systems
  • Collaborate with cross-functional teams including financial, legal and editorial colleagues to ensure high-quality information and feedback for engineering projects
  • Improve Developer Experience with managed automated preview environments, feature flags and non-production environments

Qualifications

  • Experience operating as a Senior IC Engineer, leading systems design and infrastructure discussions, mentoring junior team members, and scoping work within cross-functional product teams
  • Ability to plan and reason about software effectively, communicating its purpose and business impact
  • Hands-on experience designing data flow from storage to API endpoints with best practices for validation
  • Experience with Python and web frameworks (FastAPI with strong typing & Pydantic)
  • Strong experience delivering APIs and Service Oriented Architecture
  • Strong working knowledge of SQL for data retrieval
  • Collaborative and communicative with cross-functional teammates at 9fin
  • Commitment to code quality through testable, maintainable code and code reviews
  • Nice-to-have: experience in data modelling and with a pipeline orchestrator

Skills

Required:PythonFastAPIAPIsSQLCode reviews / mentoringSystem designCollaboration

Benefits

  • Competitive Salary (top end of market)
  • Equity options
  • Pension (minimum 4% with 9fin matching up to 7%)
  • Private Medical Insurance
  • Paid sick leave with Income Protection
  • Group Life Assurance
  • Season Ticket Loan & Cycle to Work schemes
Last updated Oct 21, 2026. Interested? Apply on the company site.
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About 9fin

Faster, smarter, debt market intelligence

9fin is a leading provider of debt market intelligence and offers everything you need to analyse a credit, or win a mandate in one AI-powered platform

Debt Market IntelligenceDataAnalyticsCredit AnalysisFinancial Data
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