Lead Full Stack Engineer (TypeScript/React)

Company: Twelve
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Lead Full-stack Engineer

London (Hybrid, 3 days on-site) | £75,000 – £100,000 depending on experience + benefits

The opportunity

We are partnering with a well-funded digital health business to find a senior engineer ready to step into a true lead role. The team is cross-functional, the codebase is modern, and the product has real-world clinical impact. You will be the technical backbone of delivery: shaping direction, writing production code, and bringing others with you.

This is not a management-track position dressed up as an IC role. You will be hands-on every day, responsible for the standard of what ships.

What the work looks like

  • Owning the frontend architecture and setting the bar for interface quality across the stack, using modern component-based frameworks.
  • Building the services and APIs that sit behind the UI, handling data flow across a thoughtfully designed system.
  • Bringing structure to cloud infrastructure and deployment pipelines, including working with infrastructure-as-code tooling.
  • Establishing testing discipline and maintaining the automated pipelines that keep quality high at pace.
  • Working closely with product and design to shape delivery, not just execute against it.
  • Exploring how AI-assisted workflows and intelligent features can be woven into both how the team works and what the platform does.

Who will thrive here

  • Proven full-stack engineers who genuinely enjoy owning both the interface layer and what powers it.
  • People who have led delivery before and know how to hold a technical vision without losing the team.
  • Strong communicators who can represent technical thinking to a non-technical room and make it land.
  • Engineers who are curious about AI, whether that means using LLM tooling day-to-day or thinking about how to deliver intelligent features in production.
  • Calm, adaptable people who do not need everything defined up front to do their best work.

The practical stuff

  • Solid experience with at least one major frontend framework alongside a working fluency in server-side development.
  • Comfortable with cloud environments and an understanding of how modern web applications are deployed and monitored.
  • Familiarity with both relational and non-relational data stores.
  • A track record of shipping within agile teams and an instinct for when process helps and when it gets in the way.

What is on offer

A salary range of £75,000 to £100,000 depending on experience, alongside a competitive permanent benefits package. You will join a team that invests in learning, runs honest retrospectives, and gives people the room to grow. Inclusive hiring is a genuine priority here, not a footnote.

Posted: April 20th, 2026