Senior Full Stack Engineer

Quantspark
London, UK
1 day ago
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Role details

Contract type
Permanent contract
Employment type
Full-time (> 32 hours)
Experience level
Expert
Experience required
5 years minimum
Working hours
Regular working hours

Tech stack

Clean Code Principles JavaScript (Programming Language) Application Programming Interfaces (APIs) Artificial Intelligence Data Analysis Software as a Service Cloud Computing Software Quality Code Review Continuous Integration Django Web Framework Python (Programming Language)
+10 more
Software Tools TypeScript Web Applications ReactJS Flask (Web Framework) Large Language Models Backend Fastapi Front End Software Development Restful APIs

Job description

Day to day, you’ll: Architect and deliver scalable, secure software for commercial clients across multiple sectors. Assess technical trade-offs and guide design decisions across projects. Write, review, and own high-quality code - primarily Python (Flask, FastAPI, or Django) and JavaScript/TypeScript (React preferred). Build and maintain RESTful APIs and modern frontends. Work directly with clients - communicating clearly, understanding the why behind what you’re building. Feed into new client proposals and help improve internal engineering processes. Mentor junior developers through code reviews, pairing, and knowledge-sharing. Use AI coding agents to accelerate delivery whilst maintaining correctness and security. AI Engineering (Required) Hands-on experience with AI coding agents in day-to-day work - prompting, iterating, reviewing generated code, validating outputs. Working understanding of LLM fundamentals and limitations (hallucinations, context windows, evaluation). Familiarity

Requirements

forward-thinking organisations across sectors: Private Equity & Financial Services: Portfolio analytics, AI-powered value creation, and risk management tools for global investment and wealth firms. Retail & Consumer: Pricing optimisation, inventory efficiency, and personalised engagement for major UK retailers and brands. Asset Management: Advanced investment platforms and automated risk management for asset managers. Public Sector: Trusted by multiple UK government departments for fraud analytics, predictive maintenance, and supply chain optimisation. SaaS & Manufacturing: Sector-spanning technology transformation for SaaS innovators and manufacturers. The Role You’ll design, build, and scale web applications across backend and frontend, owning projects from ideation through to production - architecture, CI/CD, cloud infrastructure, monitoring, the lot. We’re a small team that punches well above its weight. Client feedback is outstanding, and every engineer here has a visible impact., with prompting patterns, tool use, and concepts like RAG and embeddings. Awareness of safety and privacy concerns when using AI tools (secrets, PII, licensing). Ability to integrate AI into your workflow without compromising code quality. What We’re Looking For 5+ years’ experience as a full-stack engineer. Strong track record delivering enterprise-grade web applications and APIs. Confident across Python backend frameworks and modern frontend (React/TypeScript). Comfortable owning the full product lifecycle. Proactive, accountable, and effective in small, fast-moving teams. Clear communicator across technical and non-technical audiences. Keen to broaden into a generalist whilst deepening your core strengths - not just staying in one lane. What We Offer Tech ownership and autonomy from day one. High-impact work - you’ll see real results within months, not years. Room to innovate, not just maintain. A small, collaborative team that owns problems end to end and learns fast. Clients

About the company

ambitious enough to rethink how they use data and technology. A clear path to leading technical programmes and shaping strategy - growth here is earned, not queued. Perks & Benefits £6,000 annual training & conference budget to stay at the cutting edge Up to 6% matched pension for long-term financial security Comprehensive private healthcare via Vitality EMI share options scheme - own a piece of the growth you help create Work from anywhere in the world for up to 1 month/year 25 days holiday + buy/sell up to 5 additional days Cycle-to-work scheme for sustainable commuting Central London office stocked with refreshments, socials, and vibrant atmosphere Exclusive discounts on retail, travel, tech & fitness memberships Access to cutting-edge tools, platforms, and regular tech talks & innovation time Equal Opportunities We’re building a team that benefits from different perspectives, experiences, and ways of thinking. We know that great talent comes from all backgrounds, and we encourage applications from everyone who meets the role requirements, regardless of age, disability, gender identity, race, religion, sexuality, or any other characteristic. If you’re unsure whether you’re a perfect fit but believe you can do the job well, we’d still like to hear from you. We hire based on your skills, potential, and ability to contribute to our team, and we’re committed to a fair and objective selection process for all candidates. #J-18808-Ljbffr

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Good distractions

Talks and stories from around this role — technically off-topic, practically not.

3:33 min

Connecting frontends via a FastAPI proxy backend layer

Saoussen Chaabnia Saoussen Chaabnia · Europe 2026 Virtual

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Structuring and scaling the backend engineering team

Stefan Lingler Stefan Lingler +1 · Coffee With Developers

1:21 min

Exploring the target application for front end tests

Anna Mcdougall · JS Congress

2:35 min

Navigating framework adoption and specialized frontend hiring constraints

Chris Heilmann +2 · LIVE

1:38 min

Transitioning into backend engineering from web development

Stefan Lingler Stefan Lingler +1 · Coffee With Developers

1:42 min

Introduction to the fast API web framework

Sebastián Ramírez · World Congress 2022

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