Senior Engineer

Company: 9fin
Apply for the Senior Engineer
Location: London
Job Description:

Requirements

  • This role suits someone who has already grown beyond a typical senior remit
  • You enjoy diving into distributed systems problems, and you have firsthand experience scaling services under real production load
  • Several years operating as a senior backend engineer, with a clear track record of leading technical initiatives end to end across a product domain
  • Experience contributing to the design of distributed systems in production, including the operational realities such as failure modes, observability, data consistency, and graceful degradation
  • A track record of solving scaling problems, whether database scaling, throughput, latency, or cost. You can talk through a real example end to end: how you measured the problem, what you changed, and what the outcome was
  • Experience designing and operating event driven architectures in production, including message queues or streaming systems, with a clear understanding of delivery guarantees, idempotency, and failure handling
  • Strong design skills around APIs, service boundaries, and the flow of data from persistent storage through to clients
  • Strong Python experience, including modern web frameworks (we use FastAPI with Pydantic and strong typing)
  • Deep working knowledge of SQL and relational data modelling
  • Excellent collaboration and communication, including the ability to explain complex systems and tradeoffs to non technical stakeholders
  • A strong product and customer mindset, with the judgement to balance shipping value against long term system health
  • A high bar for code quality, testability, and operational maturity, and the habit of raising that bar through review and mentorship
  • (Desirable) Experience working on complex permissioning or access control systems (multi tenant, role or attribute based, fine grained, audit driven, or similar)
  • (Desirable) Experience with end to end document management systems, especially solving problems of scale and applying strong security practices such as encryption, access control, data lineage, and retention
  • (Desirable) Experience modernising legacy systems and migrating workloads with minimal downtime
  • (Desirable) Experience with a data pipeline orchestrator
  • (Desirable) Experience working at AI startups, including integrating with and building on top of AI and LLM based solutions
  • 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

What the job involves

  • We’re looking for a Senior Engineer II to take broad technical ownership of the backend systems powering 9fin’s platform
  • You will sit between our Senior and Staff engineering tracks
  • You will own meaningful systems end to end, lead multi sprint initiatives across a product domain, and shape how we build for scale
  • You will operate as a strong senior IC, leading design, raising the engineering bar through review and mentorship, and partnering closely with Product, Data, and our financial and legal domain experts
  • Own the design and delivery of significant backend systems and services across a product domain, from data modelling through API surface to operational concerns
  • Lead complex, multi sprint engineering initiatives that span several engineers and stakeholders
  • Drive scaling work: identify bottlenecks, propose architectural changes, and execute migrations safely in production
  • Make pragmatic decisions about distributed systems concerns including consistency, idempotency, partitioning, retries, and observability
  • Contribute to platform level discussions on service boundaries, data ownership, and how systems evolve as we enter new markets
  • Run thorough code reviews, mentor senior and mid level engineers, and help define what good looks like in the codebase
  • Partner with cross functional teammates from Product, Data Engineering, and our editorial and legal domain experts to scope work and ship the right thing
  • Improve developer experience by investing in tooling, testing, observability, and the paved road so the whole team moves faster
  • Ramp on legacy areas of the system, find the highest leverage cleanup, and execute it without stalling delivery
  • Use AI assisted engineering to move faster on understanding, prototyping, and shipping code

#J-18808-Ljbffr…

Posted: June 1st, 2026