Senior & Lead Backend Engineers (Python) | AI FinTech SaaS | US expansion | Build & Own Products, and New Features, End-to-End | £100-160k + Equity | London, Hybrid

Senior & Lead Backend Engineers (Python) | AI FinTech SaaS | US expansion | Build & Own Products, and New Features, End-to-End | £100-160k + Equity | London, Hybrid

The Company

We're working with a highly successful, fast-scaling AI b2b FinTech transforming how data and workflows operate across global financial markets.

Following significant growth, they're now heavily investing in new products and international expansion.

The Role | Senior & Lead Backend Engineers (Python) | AI FinTech SaaS | US expansion | Build & Own Products, and New Features, End-to-End | £100-160k + Equity | London, Hybrid

This is a high-impact Senior or Lead Backend Engineer position on the IC or Managerial track, taking ownership of technical strategy and architecture across a complex, rapidly scaling engineering organisation.

You'll remain hands-on when it matters, but your impact will extend far beyond your own code - setting engineering standards, solving complex architectural problems and aligning teams around a clear technical vision.

You'll be working across areas including:

• Designing and evolving large-scale backend and distributed systems
• Defining technical strategy across Platform, AI, Retrieval and shared engineering services
• Designing scalable APIs and shared platform capabilities
• Leading complex, cross-team technical initiatives from design through to production
• Improving reliability, scalability, observability and developer experience
• Working closely with AI and Retrieval teams across search, RAG and data-intensive systems
• Reducing architectural complexity and establishing common engineering patterns
• Contributing hands-on to critical technical work while raising standards through design reviews and mentoring
• Using AI-assisted engineering to improve productivity and accelerate delivery

What We're Looking For | Senior & Lead Backend Engineers (Python) | AI FinTech SaaS | US expansion | Build & Own Products, and New Features, End-to-End | £100-160k + Equity | London, Hybrid

• Strong experience designing and building large-scale backend systems and distributed architectures
• Excellent systems design skills, with evidence of making significant architectural decisions
• Experience leading technically complex initiatives across multiple engineering teams
• Strong backend programming experience with Python or another modern backend language
• Strong experience with AWS, Kubernetes, APIs and modern cloud infrastructure
• Comfortable influencing engineering strategy without direct authority
• Able to move between high-level technical strategy and hands-on engineering
• Strong communication skills with experience mentoring engineers and raising engineering standards
• Comfortable making pragmatic technical trade-offs in complex, scaling environments

Experience with AI-powered systems, RAG, search platforms, retrieval systems or vector databases would be particularly valuable.

Experience as a Founding Engineer / CTO, building systems from scratch in an early-stage environment, or modernising complex legacy systems would also be highly relevant.

What's On Offer | Senior & Lead Backend Engineers (Python) | AI FinTech SaaS | US expansion | Build & Own Products, and New Features, End-to-End | £100-160k + Equity | London, Hybrid

• Up to £160,000 base salary + equity
• Private medical insurance
• Flexible hybrid
• 25 days' holiday + public holidays
• Professional learning & development budget
• 1-month paid sabbatical after 5 years
• Significant influence over the architecture and technical direction of a rapidly scaling engineering organisation

Senior & Lead Backend Engineers (Python) | AI FinTech SaaS | US expansion | Build & Own Products, and New Features, End-to-End | £100-160k + Equity | London, Hybrid

This is an opportunity for a genuine Senior or ambitious Lead level Backend Engineer who enjoys solving difficult systems problems, influencing architecture across multiple teams and remaining close enough to the code to lead by example on Product Engineering.