Principal Engineer — Cross‑Team AI/Data Architecture

9fin; Greater London; Hybrid; GBP 120,000 - 180,000; Full time

Benefits offered by this job

Equity options

Pension

Private Medical Insurance

Hybrid working

Work abroad 3 months

Sabbatical after 5 years

Parental leave

Job summary

9fin is seeking a Principal Engineer to own the toughest technical problems across AI, analytics, platform, and product engineering in London. You will set architectural standards and own foundational data and AI infrastructure.

You will work with Heads of Analytics, AI, Platform, and Product Engineering, raise the bar across teams, mentor senior engineers, and drive decisions that shape how the company scales its data and AI foundations.

Qualifications

• Experience in data modelling and entity resolution in production environments.
• Proven experience designing and shipping AI/LLM systems—RAG, extraction, evaluation frameworks.
• Strong backend and distributed systems knowledge: APIs, service architecture, observability.
• Proven track record owning foundational architectural decisions that affected an entire org.
• Proficiency in Python; familiarity across relevant tech stack.

Responsibilities

• Own cross-cutting architectural decisions affecting multiple teams.
• Set standards for engineering quality—design, observability, reliability, APIs.
• Be the senior technical voice in cross-team planning and major buy decisions.
• Mentor and stretch the most senior engineers across the org.

Skills

Data modelling

Entity resolution

Data pipelines

AI/LLM systems

Python

Backend architecture

Distributed systems

Founding engineer

Job description

9fin is seeking a Principal Engineer to own the toughest technical problems across AI, analytics, platform, and product engineering in London. You will set architectural standards and own foundational data and AI infrastructure.

You will work with Heads of Analytics, AI, Platform, and Product Engineering, raise the bar across teams, mentor senior engineers, and drive decisions that shape how the company scales its data and AI foundations.