Principal Front-End Engineer in London

Improbable is a Venture Builder and a pioneering technology company developing next-generation networked and digital infrastructure for the web3 economy. We are working with leaders to create businesses in AI transformation, the metaverse and web3. Founded in 2012 and headquartered in London, Improbable began as an ambitious experiment to enable vast, persistent, and interactive online worlds. Over the past decade, the company has evolved into a global leader in venture building, decentralised technology, digital assets, and blockchain-enabled infrastructure, empowering creators, brands, and communities to build and scale the next era of digital experiences.

At Improbable, you are surrounded by people who want to improve everything and everyone around them, and who compel you to improve yourself. We’re motivated by the fulfilment of solving hard problems to achieve something profound and transformative.

The Role

As a Principal Frontend Engineer, you won't just be building interfaces, you will be the architectural lead for our DeFi ecosystem. You will solve the hardest problem in the space: masking the complexity of blockchain backend constraints to deliver a seamless, consumer-grade UX. You will join a collaborative, cross-functional team of friendly, adaptable, creative, and product-minded engineers who are passionate about building high-quality, user-centric software that delivers real impact.

Your Opportunity

• Shape the vision and strategy of our products by contributing to the roadmap and acting as a sounding board for technical leadership.
• Exercise cross-functional leadership, acting as the bridge between full-stack engineers, R&D engineers, and product specialists to deliver robust, production-grade services.
• Define the architecture, and implement scalable, reusable UI frameworks that power complex DeFi apps and blockchain products.
• Drive innovation by experimenting with new systems, design patterns, and tooling, while advocating for continuous improvement and engineering best practices.

We’re Looking For

• Extensive software development experience, including building and maintaining user-facing production systems.
• Frontend expertise, with deep understanding of React (ideally with Next.js), TypeScript and responsive UI design.
• Strong UI architecture skills, with the ability to apply design patterns to build simple, reusable components.
• Ability to prototype rapidly to validate ideas, then promote successful features into robust, production-grade architecture.
• Cloud experience, including hands-on work with cloud providers (ideally GCP, but AWS/Azure are acceptable).
• A tooling expert who leverages modern tooling and AI-assisted workflows (Copilot, Cursor, etc.) to accelerate personal and team velocity.
• Deep understanding of browser internals, the critical rendering path, the DOM, and networking optimizations.

Nice to Have

• Experience launching greenfield products from scratch.
• Technical understanding of blockchain technologies including DeFi and EVM ecosystem.

While we think the above experience is important, we’re very keen to hear from people who believe they have valuable experience to bring to this role. If you identify with the team and mission, but not all of our requirements, then please still apply.