At a Glance
- Tasks: Lead backend systems design and delivery, tackling complex engineering challenges.
- Company: Join 9fin, the AI platform revolutionising global debt markets.
- Benefits: Competitive salary, hybrid work, generous holiday, and professional development opportunities.
- Other info: Enjoy a dynamic culture with plenty of growth opportunities and team socials.
- Why this job: Make a real impact in a fast-growing startup with cutting-edge technology.
- Qualifications: Proven experience in backend engineering and distributed systems design.
The predicted salary is between 70000 - 90000 € per year.
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.
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. 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.
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.
- 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.
What we're looking for
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.
- 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.
Nice to have:
- Experience working on complex permissioning or access control systems (multi tenant, role or attribute based, fine grained, audit driven, or similar).
- 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.
- Experience modernising legacy systems and migrating workloads with minimal downtime.
- Experience with a data pipeline orchestrator.
- Experience working at AI startups, including integrating with and building on top of AI and LLM based solutions.
Company 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)
- 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.
Senior II Engineer in London employer: 9Fin Limited
At 9fin, we pride ourselves on being an exceptional employer that fosters a culture of innovation and collaboration. Our commitment to employee growth is evident through our generous professional development budget and opportunities for mentorship, while our hybrid working model and flexible arrangements ensure a healthy work-life balance. With competitive salaries and a range of benefits, including a month-long paid sabbatical after five years, we empower our team to thrive in a dynamic environment at the forefront of AI-driven debt markets.
StudySmarter Expert Advice🤫
We think this is how you could land Senior II Engineer in London
✨Tip Number 1
Network like a pro! Reach out to current employees at 9fin on LinkedIn or other platforms. Ask them about their experiences and any tips they might have for landing the Senior Engineer II role. Personal connections can make a huge difference!
✨Tip Number 2
Prepare for technical interviews by brushing up on your Python skills and distributed systems knowledge. We recommend doing mock interviews with friends or using online platforms to simulate the real deal. The more you practice, the more confident you'll feel!
✨Tip Number 3
Showcase your problem-solving skills! Be ready to discuss specific examples of how you've tackled scaling issues or designed APIs in previous roles. We love hearing about real-world experiences that demonstrate your expertise.
✨Tip Number 4
Don’t forget to apply through our website! It’s the best way to ensure your application gets seen by the right people. Plus, it shows you're genuinely interested in joining the 9fin team. Let’s get you on board!
We think you need these skills to ace Senior II Engineer in London
Some tips for your application 🫡
Tailor Your CV:Make sure your CV reflects the skills and experiences that align with the Senior II Engineer role. Highlight your backend engineering experience, especially with Python and distributed systems, to catch our eye!
Craft a Compelling Cover Letter:Use your cover letter to tell us why you're excited about 9fin and how you can contribute to our mission. Share specific examples of past projects where you've led technical initiatives or solved scaling problems.
Showcase Your Technical Skills:Don’t shy away from detailing your technical expertise in your application. Mention your experience with AWS, Docker, and any relevant frameworks like FastAPI. We love seeing how you’ve tackled real-world challenges!
Apply Through Our Website:We encourage you to apply directly through our website. It’s the best way for us to receive your application and ensures you’re considered for the role. Plus, it shows you’re keen on joining our team!
How to prepare for a job interview at 9Fin Limited
✨Know Your Tech Stack Inside Out
Make sure you’re well-versed in Python, Flask, FastAPI, and PostgreSQL. Be ready to discuss your experience with these technologies, especially how you've used them in distributed systems. Prepare examples of how you've tackled scaling issues or improved performance in past projects.
✨Showcase Your Problem-Solving Skills
Be prepared to walk through a real-world example where you identified a bottleneck in a system and how you resolved it. Highlight the metrics you used to measure success and the impact of your changes. This will demonstrate your analytical skills and ability to drive results.
✨Emphasise Collaboration and Communication
Since this role involves working closely with cross-functional teams, be ready to share experiences where you successfully collaborated with product managers, data engineers, or domain experts. Show how you can explain complex technical concepts to non-technical stakeholders.
✨Prepare for Design Discussions
Expect to engage in discussions about system design, service boundaries, and data flow. Brush up on your knowledge of event-driven architectures and be ready to discuss how you’ve implemented them in production. This will show that you can think critically about architecture and scalability.
