Frontend Software Engineer

Location:

UK, remote with occasional travel

In the words of one of our senior clients recently…

“Market Research has changed more in the past 3 years, than in the previous 40”

System1 is The Creative Effectiveness Platform. Our target customers are the world’s largest advertisers. We predict and improve marketing effectiveness. Our advertising and idea tests measure emotion to give our customers the most accurate predictions of the business impact of creativity.

To learn more about us, please visit System1 Group | Create with Confidence

We are looking for a talented and ambitious Frontend Software Engineer to join the empowered product team building System1’s next-generation AI platform. As our first frontend engineer on the platform, you will shape how the world’s largest brands experience AI-powered predictions of their advertising’s effectiveness, building the interfaces through which they upload video at scale, explore analytics and insights, and work with AI agents.

You will work as a first-class member of the product team alongside your Product Manager, Product Designer and Team Lead to discover and deliver outcomes that matter to our customers and our business. This is a rare opportunity to define the frontend architecture and conventions from day one, engineer in a genuinely AI-native way, and work at the speed our market demands.

• Are you energised by being a true partner in the product team, helping decide what to build, not just how to build it?

• Do you already engineer through Claude Code every day, with your own skills and subagents, and the discipline to own every line you ship?

• Are you excited by the challenge of making rich data, video and AI agents feel simple, fast and trustworthy for the people who use them?

Do you want to join us to excite and change the industry?

• Partner as a member of an empowered product team (Product Manager, Product Designer, Team Lead and engineers), sharing accountability for the outcomes your team commits to.

• Define the frontend architecture, patterns and conventions for our AI platform as our first frontend engineer, and set the bar for those who join after you.

• Build the platform’s web application in Type Script and React, creating fast, intuitive experiences for the world’s largest advertisers.

• Bring complex analytics and insights to life through data visualisation and dashboards that make our predictions clear and actionable.

• Build agentic and conversational interfaces, including streaming AI responses, that let customers work naturally alongside AI.

• Create robust experiences for uploading, processing and reviewing video at scale.

• Work API-first against a headless, spec-driven backend, consuming generated clients and helping shape the API contracts your interfaces depend on.

• Partner closely with your Product Designer, iterating rapidly from prototype to production and building a component library and design system together.

• Put automated testing at the heart of everything you ship, with a fully automated CI/CD pipeline that lets the team release with confidence.

• Engineer through Claude Code day to day, building and sharing skills, subagents and workflows that raise the speed and quality of the whole team.

• Contribute to continuous product discovery, helping the team assess feasibility early and building quick prototypes to test ideas with customers before we commit.

You need to be this kind of person:

• A missionary, not a mercenary. You care deeply about the customer problem and the outcome, not just the code.

• Outcome-driven. You measure your success by the change you create for customers and the business, not by tickets closed.

• An engineer first, with AI as a force multiplier. You use…