Senior Full-Stack AI Engineer — Frontend & LLM-Enabled UX (Level 3)

CompanyAllegis Global Solutions

LocationLondon, England, United Kingdom

Posted At1/26/2026

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Description

Job title: Senior Full-Stack AI Engineer

Location: GSK HQ

Team: Enterprise AI - Data Science UK

Contract: 6 months

Overview

GSK is a science-led global healthcare company with a special purpose: to help people do more, feel better, live longer. We are on an audacious journey to impact the health of 2.5 billion people over the next decade. Our R&D division is at the forefront of this mission, dedicated to the discovery and development of groundbreaking vaccines and medicines. We are transforming the landscape of medical research by integrating cutting-edge science and technology and harnessing the power of genetics and new data. By fostering a collaborative environment that unites the talents of our people, we are revolutionizing R&D to pre-empt and defeat diseases. Join us in our commitment to uniting science, technology, and talent to get ahead of disease together.

Role Overview

GSK are seeking a Senior Full Stack AI Engineer with a strong focus on frontend engineering, user experience and product delivery. You will lead the design and implementation of immersive, interactive web experiences that leverage large language models (LLMs) as core product capabilities. In this role you will collaborate closely with product, UX/design, ML research and platform teams to translate user needs into elegant, reliable AI-powered experiences, and drive agile delivery from prototype to production.

Key Responsibilities

Deliver highly interactive frontends (involving text based and video based chat experiences) built with modern frameworks like React that integrate LLM-driven features (conversational interfaces, tool-assisted workflows, structured editors, visualizations) to boost marketing productivity.
Enable measurement / analytics to track usage of the app and of LLM features
Own the end-to-end product experience for LLM-enabled features: collaborate with UX/design to craft flows, run rapid prototypes, and iterate based on user testing and analytics.
Integrate LLMs into the application stack, handling prompt design, response parsing, tool use, chaining, and RAG strategies while balancing latency, cost and reliability.
Implement frontend architectures and state management patterns that scale for complex, real-time, and collaborative UIs (React hooks, Context, Redux/Zustand/Recoil, server-state patterns).
Build responsive, accessible, and performant UI components and design systems (component libraries, theming, design tokens) to ensure consistent product quality and fast iteration.
Implement real-time and progressive UX patterns (WebSockets, SSE, streaming LLM responses, optimistic updates, incremental rendering) that make AI interactions feel fast and human-centered.

Collaborate on frontend work with UX designers and researchers, follow standard coding conventions, and implement best practices for design, accessibility, testing and observability.

Work with backend and platform engineers to define APIs, ingestion pipelines, vector retrieval, caching and rate-limiting strategies that support robust LLM behavior.

Drive agile delivery: break down features into deliverable increments, run sprint planning, pair with the tech PM on prioritization, and ensure production readiness through CI/CD, feature flags and canary releases.

Define and instrument UX and model-level metrics (engagement, latency, hallucination rates, user satisfaction) and use those signals to prioritize improvements.

Ensure security and privacy are integrated into the UX (PII handling, consent flows, data minimization, redaction and access controls).

Minimum Requirements

6+ years building production web applications with proven ownership of user-facing features; significant experience in frontend engineering and product delivery.
Deep expertise with React (functional components, hooks) and modern frontend ecosystems including CI/CD.

Demonstrable experience building highly interactive, immersive frontends (rich state, animations, canvas/visualizations, streaming UIs or collaborative editing).

Strong UX sensibility and experience working directly with designers to translate wireframes and prototypes to polished, accessible product UIs.

Hands-on experience integrating LLMs / generative models into applications (OpenAI, Anthropic, local/open-source LLMs): prompt engineering, response handling, safety guardrails, RAG architectures.

Good understanding of how large language models work, including transformer architecture, tokenization, attention mechanisms, decoder/encoder-decoder variants, fine-tuning/few-shot approaches, and common failure modes (hallucinations, bias, context-window limitations).

Solid backend experience (Node.js/TypeScript, Python, or similar) to collaborate on APIs, authentication, ingestion, and retrieval layers — enough to design pragmatic interfaces and own cross-stack features.

Practical experience building retrieval-augmented generation pipelines (embeddings, vector stores, chunking/indexing).

Proven track record delivering features in agile teams: sprint planning, incremental delivery, feature flagging, A/B tests and operationalizing metrics.

Strong software engineering fundamentals: testing (unit/integration/E2E), observability, performance profiling, and security-aware development.

Excellent communication skills and experience mentoring engineers and collaborating across product, design and ML teams.

Preferred Requirements

Familiarity with LLM orchestration and tools (LangChain, LlamaIndex, Haystack, OpenAI/Anthropic SDKs).
Advanced visualization/graphics skills or experience building interactive applications
Experience with design systems and component libraries (Figma workflows, design tokens)
Background in regulated industries (healthcare, pharma, finance) with awareness of compliance and data governance constraints.
Contributions to open-source projects, public talks or technical writing about LLM-enabled UX or frontend engineering.

How to Apply

Please submit your CV via the application form. If your initial application is successful, one of our recruiters will be in touch. Should you reach this stage, you will likely be required to submit the following in addition to your CV:

One or two recent projects where you led the frontend/UX for an LLM-enabled product (provide links, screenshots, architecture diagrams or repos where possible).
The primary UX decisions you made and why (trade-offs, accessibility/performance considerations).
Key technical challenges you faced (model behavior, latency, security) and how you solved them.

Why GSK?

Uniting science, technology and talent to get ahead of disease together.

GSK is a global biopharma company with a special purpose – to unite science, technology and talent to get ahead of disease together – so we can positively impact the health of billions of people and deliver stronger, more sustainable shareholder returns – as an organisation where people can thrive. We prevent and treat disease with vaccines, specialty and general medicines. We focus on the science of the immune system and the use of new platform and data technologies, investing in four core therapeutic areas (infectious diseases, HIV, respiratory/ immunology and oncology).

Our success absolutely depends on our people. While getting ahead of disease together is about our ambition for patients and shareholders, it’s also about making GSK a place where people can thrive. We want GSK to be a place where people feel inspired, encouraged and challenged to be the best they can be. A place where they can be themselves – feeling welcome, valued, and included. Where they can keep growing and look after their wellbeing. So, if you share our ambition, join us at this exciting moment in our journey to get Ahead Together.

Inclusion at GSK

GSK is an Equal Opportunity/Affirmative Action Employer. All qualified applicants will receive equal consideration for employment without regard to race, color, national origin, religion, sex, pregnancy, marital status, sexual orientation, gender identity/expression, age, disability, genetic information, military service, covered/protected veteran status or any other federal, state or local protected class.

If you need any adjustments in the recruitment process, please get in touch with our Recruitment team (EMEA-GSKLink@allegisglobalsolutions.com) to further discuss this today.

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