9fin
Senior Software Engineer (Search Platform)
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About 9fin
9fin is the AI platform powering global debt markets — the world’s largest asset class at over $145 trillion.
Debt 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.
Today, 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.
We’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.
The Opportunity
Our retrievals team is responsible for making millions of financial documents (bond deals, credit reports, legal filings, earnings transcripts) searchable and retrievable across the platform. The search layer powers every AI application we build, and the quality of retrieval directly affects product quality for our clients.
We're hiring a Senior Search Engineer to own and shape our search platform (not to maintain what exists, but to decide how it evolves).
This means you will:
Own the search platform. Design, operate, and evolve the Elasticsearch cluster and its surrounding infrastructure. You'll make the architectural decisions about how documents are indexed, searched, and served, and you'll be accountable for the system's performance, reliability, and relevance at scale. Build the tooling and APIs that other teams depend on. Backend, AI, and data engineering teams across 9fin build on top of the search platform. You'll design the interfaces, services, and guardrails that make the retrieval layer usable, reliable, and self-service where possible. Shape the search strategy. Work with product and engineering leadership to understand where search and retrieval need to go, including how the platform supports 9fin's expanding AI capabilities. You'll have direct input into the technical roadmap. Raise the bar. Run code reviews, mentor engineers, contribute to architectural discussions, and bring strong opinions about how search systems should be built. You'll be a senior IC with real influence on engineering standards.
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What we're looking for:
You must have:
Production ownership of a search platform built on Elasticsearch, OpenSearch, or a closely related technology (Solr, Vespa, Lucene). Not just usage — you've been responsible for how the system is designed, operated, and scaled. You understand internals like mappings, analyzers, shard strategies, and cluster behaviour because you've had to make real decisions about them. Experience designing and building search infrastructure — the data pipelines that feed it, the APIs that expose it, and the operational tooling that keeps it healthy. You've thought about relevance tuning, query performance, index lifecycle, and failure recovery in a production context. The ability to build for other engineers. You've created tooling, APIs, or platform capabilities that internal teams use. You understand what it takes to make a complex system accessible and reliable for people who aren't search specialists. Strong collaboration across teams. You've worked with product managers, data engineers, or other engineering teams to translate their needs into search platform capabilities. You can explain technical trade-offs clearly to non-technical stakeholders.
It would be great if you also have:
Experience with Python and modern web frameworks (we use FastAPI with strong typing and Pydantic — but we'd rather hire the right search engineer and have them pick up the language than compromise on search depth). Familiarity with distributed systems concepts — consistency, partitioning, replication — and how they apply to search infrastructure under load. Experience with cloud-managed search deployments (we run on Elastic Cloud / AWS). Exposure to how search and retrieval intersect with AI/ML systems — vector search, hybrid retrieval, or RAG pipelines.
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Our stack
Python (Flask & FastAPI), PostgreSQL, AWS (Lambda, ECS, Docker), Elastic Cloud. We have our own internal developer platform with standardised paved-road approaches to infrastructure, managed preview environments, and feature flags — so you can ship with confidence and iterate quickly.
Benefits
We’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.
Financial & Insurance
Competitive Salary (our salary bands are benchmarked at the top end of the market) Equity options Pension (your minimum contributions are 4% with 9fin matching up to 7%) Private Medical Insurance Paid sick leave with Income Protection for long periods of illness Group Life Assurance Season Ticket Loan & Cycle to Work schemes
Time off
25 holiday days per year Local public holidays (with the ability to exchange them for alternative days) Hybrid working model, to allow you the flexibility to decide how, where and when you do your best work Work abroad for up to 3 months a year 1 month paid sabbatical after 5 years of service Enhanced parental leave & flexible working arrangements available
Training & Culture
Professional learning and development budget Quarterly team socials Summer and Winter company social events
9fin is an equal opportunities employer
At 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. You might just be who we’re looking for — either for this role, or perhaps another.
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