Javascript Developer at Sanderson, London Area, £Contract Rate

Outside IR35 – 2x Senior Full-Stack JavaScript Engineer

Day Rate: £600 - £650 Outside IR35

Duration: 12-24 Month Programme – Intention to extend into 2027 F/Y

Location: Bristol / London

Working Pattern: Flexible and team-dependent. Guidance is to plan for up to one day per week in the Bristol office, plus a wider team day in-office every three months. (In practice, cadences across teams vary from weekly to once every six weeks, once a month, or once a quarter) Lots of flexibility available

A leading UK wealth management and investment platform is hiring a Senior Full Stack Engineer to join a client-facing product team responsible for the web and mobile experience that helps retail investors manage and grow their wealth ahead of retirement.

This is a product engineering role, not a ticket-taking one. You'll work in a modern agile delivery environment with frequent releases, data-driven decision making, and close collaboration with product, design, and business stakeholders.

The role:

• Build and improve client-facing experiences across web and mobile, contributing to a delivery model that prioritises quality, pace, and continuous improvement. Recent work has included the launch of new investment product types on the platform; upcoming work spans new investment services and broader platform experience improvements.

• Take full ownership of quality through automated testing, there are no manual testers here, and act as an outward-facing engineer, helping align implementation and manage dependencies across teams. Cross-team coordination is a key differentiator at this level.

• Collaborate regularly with product managers, designers, proposition managers, risk, security, pen testers, user researchers, and a Data Engineering team working towards a shared single source of truth. Sprint reviews are attended by senior business leaders, so clear communication across different audiences matters.

• Mentoring is part of the role, though it's fluid and on the job rather than formalised, identifying upskilling needs and supporting teammates as opportunities arise.

What we're looking for

Essential:

• Strong full stack engineering capability across TypeScript, React, Node and AWS
• A genuine ownership mindset around automated testing and engineering-led quality

Beneficial:

• React Native experience (mobile is in scope)
• Familiarity with Next.js, Playwright, DDD patterns, and/or Gherkin syntax

Beyond the technology, you'll need a product engineer's instincts, understanding the why and the what, challenging constructively, and working at the intersection of technology and product. Clear rationale, openness to challenge, and willingness to close knowledge gaps.