Senior Full-Stack Engineer

Department: Engineering

Location: London

Compensation: £82,000 - £123,000 / year

Description We're hiring a Senior Full-Stack Engineer to own end-to-end product development and help organisations adopt AI through reliable, high-quality software.

Our core product is proven and live with enterprise customers, and we're taking the platform to its next stage after our Seed round. You'll help improve its quality, usability, performance and reliability as usage grows, while raising our standards for how we design, build and ship.

You'll start by owning key product areas across frontend and backend, with scope to shape architecture, engineering standards and technical direction as we grow. This is a hands-on role with technical leadership and mentoring, without people management responsibilities.

What you'll own

• End-to-end product delivery: Build and own features across frontend, APIs, data and integrations, connecting AI-powered flows, learning content, authentication and the core platform into a coherent user experience.
• Engineering quality and technical direction: Make pragmatic decisions across frontend architecture, API design and data modelling; set standards for testing, maintainability and technical design; improve performance and reliability as usage grows.
• Product partnership and technical leadership: Work with your pod, Engineering manager, Product and Design to turn customer needs into robust functionality, and mentor engineers to raise the quality of what we ship.

What we're looking for We hire for aptitude, hunger and a bias to action over years of experience. This role works best for someone who wants to own a product area, set technical direction and still enjoy writing production code.

You'll bring evidence of:

• Building production web platforms across frontend and backend as a senior engineer.
• Strong experience with a modern frontend framework such as Vue, React or Angular.
• Deep experience with modern backend frameworks like FastAPI, backend services like Celery and data-driven features in a modern language. Python is preferred, but strong experience elsewhere is welcome.
• Working with relational databases and making sound technical decisions and trade-offs across a product area.
• Working closely with Product and Design to shape practical, user-centred solutions.
• Using AI-native ways of working to ship quickly without sacrificing quality.
• Curiosity about AI and how it changes the way organisations work - you don't need to be an expert when you join, but you'll want to form your own point of view quickly.

Useful but not essential:

• Vue and TypeScript; Python, FastAPI and Celery.
• Multi-tenant SaaS systems, cloud platforms such as Azure, AWS or GCP, and experience in a startup or small product team.

We know great candidates don't always tick every box. If the scope excites you and you think your experience could translate, we'd love to hear from you.

Our stack: Vue 3 and TypeScript; Python, FastAPI, Celery and Postgres; Azure with a small number of GCP services; Terraform, GitHub Actions and OpenTelemetry. You don't need this exact stack, but should be comfortable across modern production frontend and backend systems.

What you'll get

• You'll work alongside thoughtful, driven engineers and partner directly with Product, Design, the Director of Engineering and CTO, with real ownership of a platform enterprise customers rely on.
• Equity: Everyone at PAIR is offered equity, because we want everyone to share in what we build together.
• Holiday: 25 days, plus bank holidays
• Learning: access to the best AI tools and PAIR's own masterclasses
• A path to grow your career: we're an early stage company that promotes from within. As we continue to scale, the opportunities to grow with us will only increase
• Regular social events: to celebrate the wins, unwind and and enjoy the journey together!

The fine print

• This role is hybrid, with 1 day per week in our central London office
• We also come together for 7 company-wide Anchor Weeks each year (in person, Monday to Thursday).
• Visa sponsorship is available for exceptional candidates; applicants normally have the right to work in the UK.

Inclusion and adjustments We welcome applicants from all backgrounds. Every candidate for this role is assessed against the same published criteria, by interviewers using the same core questions. If you need any reasonable adjustments at any stage - a different format, more time, or flexible scheduling - just let us know.