Software Engineer

Unitary; Greater London; On-site; GBP 90,000 - 140,000; Full time

Benefits offered by this job

Flexible hours

Equity package

Pension

Parental leave

Sick leave

Development budget

Wellness budget

Team offsites

Job summary

Unitary is a remote-first AI startup building Virtual Agents. As a Senior Software Engineer, you will own the frontend for our products and help shape how customers see and trust AI-powered work, turning early builds into polished surfaces.

You will refactor the frontend into a scalable platform with a shared component library, work closely with product, design and platform engineering, and continue hands-on coding for at least the next year.

Qualifications

• Senior React engineer with production apps, including state management, performance and testing.
• Deep understanding of TypeScript, Next.js, Vite and design systems.
• Built multiple frontends at startups; moved fast without accumulating tech debt.
• Experience re-imagining/refactoring frontend codebases into scalable platforms.
• Hands-on use of AI coding agents as part of the workflow (Claude Code, Codex).
• Strong product thinking and advocacy for solid software engineering practices.
• Still hands-on and contributing for at least the next 12 months.

Responsibilities

• Own the frontend for our Virtual Agent products and evolve customer interfaces.
• Re-imagine and refactor the frontend into a scalable, reusable platform.
• Bring strong product thinking to every screen you build.
• Bridge Product, Design and Platform Engineering to deliver robust frontend code.

Skills

React

TypeScript

Next.js

Design systems

State management

Performance

Testing

AI coding agents

Frontend architecture

Tools

Claude Code

Codex

Job description

We're a fast growing AI startup on a mission to help midmarket businesses transform how work gets done.

We've built a factory for custom operations agents. The factory builds Virtual Agents: software workers with AI reasoning that complete complex workflows end-to-end, directly in customer tools. There's no tech integration, process change or upfront cost. Onboarding is white-glove, takes a matter of days, and customers pay only for delivered value.

This makes Virtual Agents the lowest risk way to automate complex manual work. And it makes Unitary the first company delivering Fortune 500-grade AI deployment with the unit economics of software - enabling us to reach the midmarket at scale.

Today we're focused on commercial insurance, marketplaces and primary healthcare. But the potential for Virtual Agents goes far beyond.

We closed $15M Series A funding in 2024, and we're backed by some leading names in AI (Plural and Creandum). We're working with world-class clients such as Substack, Trustpilot, Depop, Sony Interactive Entertainment, and many more.

This is an exciting opportunity to join a well-funded startup at a crucial stage of growth, and to play a significant part in turning frontier AI technology into real world value.

The Role

As a Senior Software Engineer you will:

• Own the frontend for our Virtual Agent products
  • Our customers interact with the outputs of our Virtual Agents through interfaces you will build and evolve. As we productise our offering, you will be the person shaping how customers see, trust and control AI-driven work - taking these interfaces from early, pathfinder builds into polished, reliable product surfaces.
• Re-imagine and refactor our existing frontend into a scalable, reusable platform
  • Our current frontend has helped us grow from 0 to 25 clients in the past 18 months, largely built to unblock individual customers. We now need it re-imagined as a proper platform: a shared component library, consistent patterns and a codebase that lets us ship new customer-facing features quickly and confidently as we scale.
• Bring strong product thinking to every screen you build
  • You won't just be handed designs to implement. You will work closely with product and design to shape what we build, pushing back where needed, and using your judgement to make the product simpler and more useful for customers.
• Bridge our Product, Design and Platform Engineering capabilities
  • You will be the person who turns product and design intent into robust, production-grade frontend code, while working closely with our platform and backend engineers to make sure the frontend is well supported by the APIs and services underneath it.

The role will report to a Principal Engineer and can be based in the UK or alternatively anywhere within 3 hours of the UK timezone.

You

We are looking for someone who is excited about building innovative solutions and wants to have a large impact in a smaller company; you will be a key part of defining Unitary's future during this early stage of our next growth journey. We need versatile people who are happy to get stuck into whatever needs doing, and are ready to learn and grow with the company.

For this particular role, we need a senior, product-minded React engineer who has built and shipped frontends at startups before, ideally more than once. You will be comfortable owning a frontend end-to-end - from architecture and component design through to the small UX details that make a product feel great to use. Communication is crucial, as you will work closely with colleagues across product, design and platform engineering to bring their work together into experiences customers love.

We would love to hear from you if you:

• Have deep, expert-level experience building production React applications, including state management, performance and testing
• Deep understanding of TypeScript, modern React tooling (e.g. Next.js, Vite) and design systems
• Have built multiple frontends from the ground up at startups, and understand the tradeoffs of moving fast without accumulating unmanageable technical debt
• Have experience re-imagining and refactoring frontend codebases so they scale reliably as a product and team grow (e.g. component libraries, design systems, shared tooling)
• Use AI coding agents as a core part of how you work, with hands-on experience of agentic tools (e.g. Claude Code, Codex)
• Have strong product thinking and instincts - you care as much about whether a feature is right as whether it is well built
• Are an advocate of strong software engineering practices, standards, and culture
• Are still building hands-on and want to keep doing so for at least the next 12 months

It would be even better, but not essential, if you have:

• Previous experience as an early or founding engineer at a startup
• Some full-stack exposure, and are comfortable venturing into backend or API work when needed
• Experience designing frontend architecture for AI-driven or data-heavy products

About us

The team

Unitary is a remote-first team of 25+ people spread across Europe who are fiercely passionate about making the internet a better place, and deeply motivated to become a force for good. We have an ambition to create a company filled with happy, kind and collaborative people who achieve extraordinary things together. Our culture is built around the power of trust, transparency and self-leadership.

Working at Unitary

We are committed to creating a positive and inclusive culture built on genuine interest for each other's well-being. We offer progressive and market-leading benefits, including:

• Flexible hours and location
• Competitive salary and equity package
• Occupational pension
• Generous paid parental leave
• Generous paid sick leave
• Annual budget for your professional development and growth
• Annual budget for your individual health and wellness
• Three team offsites to London or other exciting destinations in Europe