Senior Full-Stack Software Engineer in London

Who We Are

PAIR is a fast-growing AI adoption startup on a mission to help professionals and teams harness AI to do their best work. Our platform delivers personalised, AI-powered learning experiences and adoption support that help organisations rapidly harness AI at scale. We've already achieved:

• 15,000+ users
• Major enterprise deployments live today with the likes of the Ministry of Justice, you.com and The MTC
• Backing from top-tier UK investors including Seedcamp, Venrex, Tom Hulme (Google Ventures) & Steve Garnett (ex-Chairman EMEA, Salesforce)

We're a small, high-calibre team that ships fast. Engineers here have a direct and visible impact on the product, users, and company trajectory. If you want meaningful ownership and an environment that values great engineering, you'll thrive. You're joining after our Seed round, at a point where the core product is proven and live with enterprise customers, with huge scope to shape product, architecture, standards and technical direction as we take the platform to the next level.

The Role

We're hiring a Senior Full-Stack Engineer to help lead the development of our product platform across frontend and backend. You'll be responsible for building high-quality end-to-end product features while raising the bar for how we design, build and ship reliable software across the stack. This is a hands-on senior engineering role: you'll write production code, own key technical decisions, work closely with product and design, and mentor other engineers, without people management responsibilities.

You'll:

• Build end-to-end product features, from backend APIs and data models through to polished frontend UI
• Set standards for full-stack quality, testing, maintainability and pragmatic technical design
• Work closely with the CTO, EM, product and design to translate customer needs into robust, user-facing functionality
• Make pragmatic technical decisions across frontend architecture, API design, data modelling and integrations
• Improve the quality, usability, performance and reliability of the existing platform as usage grows
• Own the full-stack role of key product areas, connecting AI-powered flows, learning content, authentication, core platform capabilities and user experience

Our Stack

Frontend: Vue 3, TypeScript
Cloud: Azure as primary (plus a small number of services on GCP)
Infra & DevOps: Terraform, GitHub Actions, OpenTelemetry

You don't need to know this exact stack, but you should be very comfortable working across a modern web application and able to make sound technical decisions across both frontend and backend systems in production.

What We're Looking For

We're looking for a genuine senior full-stack engineer who can take ownership, set direction and still enjoy writing code.

Must-have experience:

• Strong track record as a senior engineer building production web platforms across frontend and backend
• Strong experience with at least one modern frontend framework (Vue, React or Angular)
• Deep experience building APIs, backend services and data-driven product features in a modern language (Python preferred, but strong experience elsewhere is fine)
• Experience owning end-to-end technical design in a small or mid-sized engineering team
• Solid experience working with relational databases
• Comfort being the go-to person for technical decisions and trade-offs across a product area
• Comfort working closely with product and design to shape practical, user-centred solutions
• Pragmatic mindset: you value clarity, reliability and simplicity over over-engineering

Nice to have:

• Vue and TypeScript experience
• Python + FastAPI experience
• Experience with multi-tenant SaaS systems
• Familiarity with cloud platforms (Azure, AWS or GCP)
• Experience stabilising or improving an existing codebase rather than starting greenfield
• Experience working in a startup or small product team

We care much more about what you've built and shipped than the exact technologies you've used.

Why Join PAIR?

• Real impact: You'll help shape the product platform that enterprise customers rely on.
• Ownership: This is not a narrow role: you'll have real technical authority and responsibility across the stack.
• Work closely with the product: You'll collaborate directly with product and design and see how your work impacts customers.
• A-player environment: We hire carefully. You'll work with thoughtful, driven engineers who care about their craft.
• Backed by top investors: Strong financial footing and backing from some of the best with meaningful revenue traction.
• Mission: Help people and organisations use AI confidently, not fear it.

Compensation & Working Setup

• Equity: competitive, depending on experience and level
• Hybrid: 1 day/week in our central London office (Tuesdays)
• Anchor Weeks: 7 company-wide Anchor Weeks (in-person Mon-Thu) each year for deep collaboration
• Paid Leave: 25 days holiday + public holidays
• Right to work: We can sponsor visas for exceptional candidates; applicants normally have UK work rights

Hiring Process

We keep the process simple and respectful of your time:

• Application form - basic details, skills matrix and a short case-study question.
• Short self-paced technical exercise - practical and focused on full-stack engineering, product thinking and technical reasoning
• Technical interview (remote) - walk through your exercise + deeper discussion of your experience
• Final stage - meet the team in person and talk about how you'd help us scale PAIR over the next 12-24 months