Principal Software Engineer Python AI - FinTech

Client Server Ltd.; Greater London; Hybrid; GBP 100,000 - 120,000; Full time

Benefits offered by this job

Pension

Job summary

Client Server Limited is recruiting a Principal Software Engineer (Python AI) for a FinTech environment in London. The role blends hands-on Python development with technical ownership, shaping product architecture and delivering new capabilities across backend, data processing and financial systems.

The position offers a hybrid working model, with three days in the City office and two days remote, and a salary up to £120k with pension benefits and strong development opportunities.

Qualifications

• Strong academic background with Oxbridge or Russell Group university and a 2.1+ in a STEM discipline (Computer Science preferred).
• Extensive commercial software engineering experience at Senior/Principal level.
• Expertise with Python development and Django or FastAPI, with ability to lead design from concept to production.
• Experience in AI and LLMs and applying them to products and development workflows.
• Ability to shape technical architecture and influence engineering decisions.
• Product-focused mindset balancing new development with improving existing systems.

Responsibilities

• Lead projects end to end, shaping architecture and driving delivery of new product capabilities.
• Hands-on Python development and collaboration across backend, data processing, and financial systems.
• Drive adoption of AI/LLM technologies across the engineering team.

Skills

Python development

AI/LLMs

Leadership of projects

Product-minded

Architectural thinking

FinTech domain knowledge

Education

Oxbridge or Russell Group degree

2.1+ in STEM (Computer Science preferred)

Tools

Django

FastAPI

Python

Job description

Principal Software Engineer Python AI - FinTech

London, Greater London | £100k - £120k per year

Principal Software Engineer / Developer (Python AI) London / WFH to £120k

Do you have expertise with backend Python combined with a strong knowledge of Agentic AI?

You could be progressing your career at an established FinTech business specialising in automated investment reporting .

As a Principal Software Engineer you'll be in a product focused engineering role, combining hands-on Python development with technical ownership. You'll lead projects end to end, shape architecture and drive the delivery of new product capabilities, working across backend engineering, data processing and complex financial systems.

The business is also embracing AI and LLM technologies and is looking for someone who can bring a modern approach to engineering, identify practical applications and help drive adoption across the team.

Location / WFH:

You'll join the team in the London, City based office three days a week with flexibility to work from home the other two days.

About you:

• You have a strong academic background, educated at Oxbridge or a Russell Group university, having achieved a 2.1 or above in a STEM discipline, Computer Science preferred
• You have strong commercial software engineering experience, at Senior or Principal level
• You have expertise with Python development combined with experience using Django or FastAPI (happy to use Django going forward)
• You can lead the design and delivery of software products and take projects from initial concept through to production
• You have experience with AI and LLMs, with a genuine interest in applying them to products and development workflows
• You have experience shaping technical architecture and influencing engineering decisions
• You have a product focused mindset, with the ability to balance new development with improving existing systems
• Experience in FinTech, financial services or investment technology would be advantageous but not essential

What's in it for you:

• Salary to £120k
• Pension
• Impactful role with excellent development opportunities