9fin - Senior II Engineer

• 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. • OUR BACKEND STACK • Python is the dominant backend language. • Flask and FastAPI, with strong typing and Pydantic powering automated documentation and API definitions. • PostgreSQL at the heart of most services. • AWS for cloud hosted services, with heavy use of AWS Lambda serverless. • Docker on AWS ECS for uniform development and deployment. • Internal developer platform with a standardised paved road from code to production, plus managed preview environments and feature flags. • 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.