Lead Software Developer

We are a London-based FinTech start-up specialising in asset-backed finance and private credit—also known as structured finance. By combining deep capital markets expertise with our in-house SaaS technology platform, we streamline transaction onboarding, data management, and performance monitoring. This unique blend of technology and financial know-how gives our clients operational leverage and strengthens their investment and asset management capabilities.

Our platform has the potential to shape the everyday decision-making of financial services, giving our clients smarter insights and the ability to streamline all their processes, resulting in more efficient financing throughout the economy.

As demand for our product grows, we are expanding our team and we\’re looking for a Lead Software Developer/Tech Lead to help us scale to the next level.

At Five Sigma Finance, you will be part of a pioneering journey at the intersection of finance and technology.

Job purpose

Our tech team of 10–15 engineers is highly collaborative and driven by technical excellence. Most focus on backend development (Python/Django/FastAPI), with two frontend engineers ), a couple of full-stack developers, and an infrastructure specialist.

We\’re seeking a hands-on technical leader to support and guide the team — ensuring we continue to deliver a high-performance, scalable SaaS platform.

This is an opportunity for a technically strong developer (7+ years\’ experience) who naturally helps set priorities, remove blockers, and who fosters a supportive, high-performing culture. You will balance coding (initially ~60–70% of your time) alongside leadership and mentoring, transitioning toward greater team management as the company scales.

Day to day responsibilities:

• Design, develop, and optimise core components for our SaaS platform and data pipelines.
• Develop, review, and refactor code to maintain high-quality standards.
• Collaborate with leadership to define technical strategy and product direction.
• Drive the development of scalable, reliable systems used by major financial institutions.
• Balance hands-on coding with people management and mentorship.
• Foster a culture of collaboration, learning, and continuous improvement.
• Guide and mentor developers across experience levels, helping them grow.

You will thrive in this role if you have:

• 7+ years of software engineering experience with strong Python expertise.
• Proven experience building and scaling backend systems.
• Exposure to one or more of: Spark, ClickHouse, ETL frameworks, dashboarding tools, data modelling, web frameworks, or API design.
• Adaptability and problem-solving skills suited to fast-moving start-up environments.
• A track record of mentoring or leading small teams.
• Excellent communication and collaboration skills.

Desirable attributes:

• Prior or current experience managing or leading engineering teams (line management optional).
• Experience in start-up or scale-up environments.
• FinTech or fixed income background.
• Regular collaboration with CTOs or technical founders.

Our tech stack

We primarily work with:

• Backend: Python, Django, Pydantic, PostgreSQL, DuckDB
• Frontend: React, TypeScript,
• Infrastructure: AWS, Docker, Terraform, CI/CD pipelines

Job details:

• Job Purpose:
  Support the CTO in leading the engineering team while remaining hands-on.
• Reporting Line:
  CTO
• Contract Type:
  Full-time
• Location:
  Blackfriars, Central London (Hybrid)
• In-Office Expectations:
• During probation (4 months): 4 days in office / 1 from home
• Post-probation: 3 days in office / 2 from home
• Hours:
  9:00 – 17:30 (lunch hour included and flexibility required during busier periods)
• Compensation:
  £90,000–£110,000 (depending on experience) + discretionary bonus (up to 25%)