Job Description:

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:
  • TypeScript
  • React
  • Node.js
• Proven 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 AI
• Large Language Models (LLMs)
• Agentic AI
• Docker
• CI/CD
• Infrastructure as Code
• Microservices
• Event-driven architecture
• AWS
• Google 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:

• React
• TypeScript
• Node.js
• AWS
• Google Cloud Platform (GCP)
• Vertex AI
• REST APIs
• Large Language Models (LLMs)
• Agentic AI
• Git
• CI/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 salary
• Permanent position
• London-based
• 4 days per week in the office
• Opportunity to join a small, high-performing AI startup at an early stage
• Direct exposure to the founding team
• Significant influence over technical direction and architecture
• Opportunity to work with modern AI development tools and technologies
• Genuine ownership and responsibility from day one

If 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.