Senior Full-Stack Engineer - AI

Senior Full-Stack Engineer - AI Startup (Typescript, Node, React) London - 4 days per week in the office Permanent | £120,000 - £150,000 We're working with an exciting early-stage AI startup building an agentic platform for institutional finance. The company is a small, high-performing team of fewer than 10 people, moving quickly and building towards its next stage of growth and investment. This is an opportunity for a senior engineer to join at an early stage and play a significant role in shaping both the product and technical direction of the business. The Role As a Senior Full-Stack Engineer, you'll act as a key technical contributor within a small engineering team. You'll work across the entire technology stack - from database and backend development through to the user interface - while taking ownership of the software you build through to production and beyond. Working closely with the founding/lead engineer and founders, you'll have significant influence over architecture, engineering practices and the way the product evolves as the company scales. Key Responsibilities Build and deliver end-to-end product functionality across the full stack.Develop and maintain high-quality production software.Work across backend, frontend, database and API development.Contribute to technical architecture and engineering decisions.Take ownership of features from concept through to production.Work closely with founders and engineering leadership to shape the product roadmap.Help establish strong engineering standards as the team grows.Use modern AI-assisted development tools to accelerate development and productivity.Troubleshoot, maintain and continuously improve production systems.Contribute to the development of AI-powered and agentic solutions. What We're Looking For This is an early-stage hire, so we're looking for someone who brings more than just strong technical ability. You should be genuinely excited by the opportunity to work in a small team, take ownership and help build something from an early stage. Essential Experience 8+ years' commercial software engineering experience.Strong full-stack development experience with no significant frontend or backend bias.Recent, hands-on experience with: TypeScriptReactNode.jsProven experience building and maintaining production software.Experience taking ownership of projects and features from development through to production.Regular use of modern AI coding/development tools, such as Claude Code, Cursor or similar.Strong understanding of software engineering principles and architecture.Experience working with APIs, cloud platforms and modern software development practices. Startup Experience Previous experience working within a startup or early-stage technology business is highly desirable. We're particularly interested in engineers who have: Joined a company at a very early stage.Been one of the first 4-5 engineers.Worked as a founding engineer or similar.Helped take a product from an early stage through meaningful growth.Thrived in environments where engineers have significant ownership and responsibility. Desirable Skills Experience with some of the following would be highly advantageous: Vertex AILarge Language Models (LLMs)Agentic AIDockerCI/CDInfrastructure as CodeMicroservicesEvent-driven architectureAWSGoogle Cloud Platform (GCP)You don't need to have experience with every technology listed, but a strong interest in modern AI engineering and cloud-native development would be highly beneficial. Technology Stack The current technology environment includes: ReactTypeScriptNode.jsAWSGoogle Cloud Platform (GCP)Vertex AIREST APIsLarge Language Models (LLMs)Agentic AIGitCI/CD The Person We're looking for someone who is: Entrepreneurial and genuinely excited by startup environments.Comfortable working with ambiguity and moving quickly.Highly motivated and proactive.Comfortable taking ownership rather than waiting for detailed instructions.Interested in AI and how it is changing software development.A strong communicator who enjoys working closely with founders and technical leadership.Able to balance speed with producing reliable, maintainable production software.Excited by the opportunity to help shape a product and engineering function from an early stage. What's on Offer? £120,000 - £150,000 salaryPermanent positionLondon-based4 days per week in the officeOpportunity to join a small, high-performing AI startup at an early stageDirect exposure to the founding teamSignificant influence over technical direction and architectureOpportunity to work with modern AI development tools and technologiesGenuine ownership and responsibility from day oneIf you're a senior full-stack engineer who enjoys building, taking ownership and working in an early-stage AI environment, we'd be keen to hear from you. Desired Skills and Experience Senior Full-Stack Engineer - AI Startup London - 4 days per week in the office Permanent | £120,000 - £150,000