{"id":15457,"url":"https://alion.io/job/9fin-senior-ii-product-engineer","title":"Senior II Product Engineer","company":{"id":4757,"name":"9fin","domain":"9fin.com","url":"https://alion.io/company/9fin","size_band":"201-500","is_staffing_agency":false,"employer_type":"direct","is_intermediary":false,"listed_via":null,"ats_vendor":"Ashby","truth_index":{"grade":"B","score":81,"open_postings":9,"ghost_share":0,"stale_share":0.778,"repost_share":0,"time_to_fill_p50_days":45,"computed_at":"2026-10-25T05:49:26Z"}},"role":"Backend","role_family":"Backend","seniority":"senior","employment_type":"full_time","work_mode":"hybrid","remote_scope":null,"remote_scope_basis":null,"remote_working_hours":null,"hiring_geo_confidence":"structured","locations":["London, United Kingdom"],"countries":["GB"],"hiring_countries":[],"hiring_countries_total":0,"salary":null,"salary_estimate":{"min_usd":106000,"max_usd":208000,"period":"year","method":"role_seniority_country_remote_cell","sample_n":130},"experience_years_min":null,"visa_sponsorship":false,"relocation_package":false,"has_equity":false,"technologies":[{"name":"Amazon ECS","optional":false},{"name":"AWS","optional":false},{"name":"AWS Lambda","optional":false},{"name":"Docker","optional":false},{"name":"FastAPI","optional":false},{"name":"Flask","optional":false},{"name":"PostgreSQL","optional":false},{"name":"Pydantic","optional":false},{"name":"Python","optional":false},{"name":"SQL","optional":false},{"name":"LLM","optional":true}],"status":"live","first_seen_at":"2026-05-20T09:33:00Z","employer_posted_date":"2026-05-20","last_verified_at":"2026-10-25T05:22:20Z","board_verified":true,"closed_at":null,"days_open":157,"trust":{"level":"stale","repost_count":0,"flags":["stale"],"days_open":157},"description":"About 9fin\n9fin is the AI platform powering global debt markets - the world’s largest asset class at over $145 trillion.\nDebt markets are vast, global, and mission-critical, yet still run on fragmented data, PDFs, and manual workflows. 9fin replaces this broken infrastructure with a single platform that centralises proprietary credit data, deep analysis, and high-value workflows across global markets.\nToday, 9fin powers teams at 300+ blue-chip institutions worldwide, including global banks, asset managers, private equity firms, law firms, and advisors. The business is scaling at exceptional speed, with rapid expansion in the US and best-in-class retention driven by deep workflow adoption.\nWe’re at a defining inflection point. With proven product-market fit and strong, global market pull, 9fin is accelerating toward becoming the category-defining platform for debt markets worldwide.\nWe're looking for a Senior II Product Engineer to take broad technical ownership of the backend systems powering 9fin's platform.\nYou 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.\nThis 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.\nWhat you'll do\nOwn the design and delivery of significant backend systems and services across a product domain, from data modelling through API surface to operational concerns.\n\nLead complex, multi sprint engineering initiatives that span several engineers and stakeholders.\n\nDrive scaling work: identify bottlenecks, propose architectural changes, and execute migrations safely in production.\n\nMake pragmatic decisions about distributed systems concerns including consistency, idempotency, partitioning, retries, and observability.\n\nContribute to platform level discussions on service boundaries, data ownership, and how systems evolve as we enter new markets.\n\nRun thorough code reviews, mentor senior and mid level engineers, and help define what good looks like in the codebase.\n\nPartner with cross functional teammates from Product, Data Engineering, and our editorial and legal domain experts to scope work and ship the right thing.\n\nImprove developer experience by investing in tooling, testing, observability, and the paved road so the whole team moves faster.\n\nRamp on legacy areas of the system, find the highest leverage cleanup, and execute it without stalling delivery.\n\nUse AI assisted engineering to move faster on understanding, prototyping, and shipping code.\n\nOur backend stack\nPython is the dominant backend language.\n\nFlask and FastAPI, with strong typing and Pydantic powering automated documentation and API definitions.\n\nPostgreSQL at the heart of most services.\n\nAWS for cloud hosted services, with heavy use of AWS Lambda serverless.\n\nDocker on AWS ECS for uniform development and deployment.\n\nInternal developer platform with a standardised paved road from code to production, plus managed preview environments and feature flags.\n\nWhat we're looking for\nYou will be a great fit if you have:\nSeveral years operating as a senior backend engineer, with a clear track record of leading technical initiatives end to end across a product domain.\n\nExperience contributing to the design of distributed systems in production, including the operational realities such as failure modes, observability, data consistency, and graceful degradation.\n\nA 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.\n\nExperience 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.\n\nStrong design skills around APIs, service boundaries, and the flow of data from persistent storage through to clients.\n\nStrong Python experience, including modern web frameworks (we use FastAPI with Pydantic and strong typing).\n\nDeep working knowledge of SQL and relational data modelling.\n\nExcellent collaboration and communication, including the ability to explain complex systems and tradeoffs to non technical stakeholders.\n\nA strong product and customer mindset, with the judgement to balance shipping value against long term system health.\n\nA high bar for code quality, testability, and operational maturity, and the habit of raising that bar through review and mentorship.\n\nNice to have:\nExperience working on complex permissioning or access control systems (multi tenant, role or attribute based, fine grained, audit driven, or similar).\n\nExperience 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.\n\nExperience modernising legacy systems and migrating workloads with minimal downtime.\n\nExperience with a data pipeline orchestrator.\n\nExperience working at AI startups, including integrating with and building on top of AI and LLM based solutions.\n\nCompany Benefits\nWe’re a scaling start up and we enjoy sharing our success, when the company succeeds, we always reinvest that in our people. We also offer huge amounts of responsibility, an abundance of opportunity for growth and a platform to truly excel.\nFinancial & Insurance\nCompetitive Salary(our salary bands are benchmarked at the top end of the market)\n\nPension (your minimum contributions are 4% with 9fin matching up to 7%)\n\nPrivate Medical Insurance\n\nPaid sick leave with Income Protection for long periods of illness\n\nGroup Life Assurance\n\nSeason Ticket Loan&Cycle to Work schemes\n\nTime off\n25 holiday days per year\n\nLocal public holidays (with the ability to exchange them for alternative days)\n\nWork abroad for up to 3 months a year\n\n1 month paid sabbatical after 5 years of service\n\nEnhanced parental leave&flexible working arrangements available\n\nTraining & Culture\nProfessional learning and development budget\n\nQuarterly team socials\n\nSummer and Winter company social events\n\nHybrid Policy\n9fin is a hybrid company, and the office is a regular part of how we work. From January 2027, all employees will work from their designated 9fin office on Tuesdays and Wednesdays. Some teams may be asked to be in the office more often, where the nature of their work calls for it. For the rest of the week, you may work from wherever works best for you and your team. Your Talent Partner will share hybrid working details for this role.\n9fin is an equal opportunities employer\nAt 9fin we are dedicated to building and promoting a fair and inclusive workplace where everyone can reach their full potential and truly belong. We recognize that building diverse teams enables a more creative and productive environment. If you’re excited about this role but your experience doesn’t perfectly align with the job description, we encourage you to apply anyway. 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