Senior II Product Engineer

About the role

You will own the design and delivery of significant backend systems and services that form the core of 9fin's debt markets platform, ensuring they meet stringent requirements for scale, reliability, and performance. You will lead complex, multi-sprint engineering initiatives that span multiple engineers and diverse stakeholders, driving initiatives from initial concept through to production deployment and optimization. This role requires you to make pragmatic distributed systems decisions around consistency, idempotency, partitioning, retries, and observability while balancing product value against long-term system health. You will partner closely with Product, Data Engineering, and our editorial and legal domain experts to scope work, define requirements, and execute solutions that address real market needs. You will operate as a strong senior IC, leading code reviews, mentoring engineers, and raising the engineering bar by defining and enforcing standards for quality and best practices. This position involves ramping on legacy areas of the system, identifying the highest leverage cleanup opportunities, and executing improvements without stalling delivery momentum. You will also utilize AI-assisted engineering tools to accelerate understanding, prototyping, and shipping code, thereby enhancing individual and team productivity.

Key facts

What you'll do

• 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 to ensure aligned execution.
• Drive scaling work by identifying bottlenecks, proposing architectural changes, and executing migrations safely in production environments.
• Make pragmatic decisions about distributed systems concerns including consistency, idempotency, partitioning, retries, and observability to maintain robust services.
• Contribute to platform-level discussions on service boundaries, data ownership, and how systems evolve as we enter new markets and expand globally.
• Run thorough code reviews, mentor senior and mid-level engineers, and help define what good looks like in the codebase to maintain high standards.
• Partner with cross-functional teammates from Product, Data Engineering, and our editorial and legal domain experts to scope work and ship the right solutions efficiently.
• Improve developer experience by investing in tooling, testing, observability, and the paved road so the whole team can move faster with confidence.
• Ramp on legacy areas of the system, find the highest leverage cleanup opportunities, and execute necessary improvements without delaying delivery timelines.
• Use AI-assisted engineering to move faster on understanding, prototyping, and shipping code while maintaining quality and accuracy.

Requirements

You will be a great fit if you have several years operating as a senior backend engineer, with a clear track record of leading technical initiatives end to end across a product domain that impacts critical financial workflows. You have experience contributing to the design of distributed systems in production, including the operational realities such as failure modes, observability, data consistency, and graceful degradation under load. You possess a track record of solving scaling problems, whether related to database scaling, throughput, latency, or cost, and you can discuss a real example end to end, explaining how you measured the problem, what changes you implemented, and what the outcome was. You have designed and operated event-driven architectures in production, including message queues or streaming systems, with a clear understanding of delivery guarantees, idempotency, and failure handling strategies. You demonstrate strong design skills around APIs, service boundaries, and the flow of data from persistent storage through to clients, ensuring robust and maintainable interfaces. You have deep working knowledge of SQL and relational data modelling, enabling you to construct efficient queries and schema designs that support platform needs. You bring strong Python experience, including modern web frameworks such as FastAPI with Pydantic and strong typing, to build reliable and well-structured services. You communicate excellently, with the ability to explain complex systems and tradeoffs to non-technical stakeholders while fostering collaboration across teams. You maintain a strong product and customer mindset, exercising judgement to balance shipping value against long-term system health and operational stability. You uphold a high bar for code quality, testability, and operational maturity, and you habitually raise that bar through thorough review and mentorship of peers and junior engineers.

Practical notes

This is a full-time role based in London.