Lead Full-Stack Developer

The Gym Limited; London Borough of Wandsworth; Hybrid; GBP 90,000 - 130,000; Full time

Job summary

The Gym Group is seeking a Lead Full-Stack Developer to drive architecture and delivery across React/Next.js and .NET Core in a hybrid setup based in London. You will mentor engineers, shape technical direction, and collaborate with product, design, architecture, and partners to deliver high-quality digital experiences.

You will design and govern AI-assisted tooling, manage Azure cloud infrastructure, and promote best practices like TDD, SOLID, and DevSecOps.

Qualifications

• Five+ years of commercial software development experience, with at least two years in a lead or senior role.
• Hands-on full-stack expertise across React/Next.js and .NET Core.
• Proven experience with Azure cloud services and Infrastructure as Code (Terraform or Pulumi).

Responsibilities

• Lead full-stack development across value streams, owning quality and delivery outcomes.
• Set technical direction across the stack, balancing SSR vs client rendering and API design.
• Mentor engineers, build team culture, and support professional growth.
• Define and govern AI-assisted development tools with guardrails.
• Design and manage Azure cloud infrastructure with Terraform/Pulumi.
• Promote TDD, SOLID, event-driven architecture, and DevSecOps.

Skills

React/Next.js

.NET Core

Azure

Terraform

Pulumi

CI/CD (Azure DevOps)

Docker

Kubernetes

TDD/BD

SO LID & event-driven

Lead through influence

Tools

Terraform

Pulumi

Azure DevOps

Docker

Kubernetes

Job description

Role: Lead Full-Stack Developer

Location: Hybrid - 3 days per week in Clapham Junction

Who we are...

We're not like any other gym company; we are The Gym Group, a place where you can #BeYouWithUs and perform to your absolute best. We are successful; by membership we're the 2nd largest gym business in the UK and the 4th largest in Europe. We hire people with real passion, positivity and enthusiasm which motivates and inspire those around them. We actively invest in our employees; it's so important to us that our people can thrive in our environment and can make the most of the flexibility and support we offer to all of our teams.

What you'll be doing...

• Leading full-stack development across value streams, owning technical quality, delivery outcomes, and team capability growth
• Setting technical direction across the stack - making pragmatic trade-offs on things like SSR versus client rendering, API design, and architecture patterns with maintainability in mind
• Contributing to low-level solution design alongside the Architecture team, helping turn complex technical requirements into clear, deliverable plans
• Mentoring developers, building a strong team culture, and actively supporting the professional growth of engineers around you
• Defining and governing the use of AI-assisted development tools across the team, including setting guardrails and identifying genuinely high-leverage opportunities
• Designing and managing Azure cloud infrastructure using Kubernetes, Service Bus, APIM, and Key Vault, with IaC via Terraform or Pulumi
• Driving adoption of software engineering best practices including TDD, SOLID principles, event-driven architecture, and DevSecOps
• Collaborating closely with Product, UI/UX, Architecture, and third-party engineering partners to deliver high-quality digital experiences

What we’re looking for...

• Five or more years of commercial software development experience, including at least two years in a lead or senior technical role
• Hands-on full-stack expertise across React/Next.js and .NET Core
• Proven experience with Azure cloud services and Infrastructure as Code (Terraform or Pulumi)
• Familiarity with CI/CD tooling (Azure DevOps preferred) and containerisation with Docker
• Strong grounding in software engineering best practices - TDD, BDD, SOLID, and architectural patterns such as event-driven and serverless
• Ability to lead through influence and communicate clearly with both technical and non-technical audiences

Our commitment to inclusion

At The Gym Group we are committed to creating an inclusive environment where everyone feels welcome to be themselves. We celebrate diversity and know that our teams are stronger for it. We encourage applications from people of all backgrounds, identities and experiences – your perspective matters here.

We also want to put it out there that we actively encourage applications from a diverse demographic and we are passionate about your culture and value alignment. We want this to be a match that works for you as much as for us!

Please note that we may close the application window early if we receive high levels of interest.

Your application may be reviewed by an AI tool to help assess your suitability based on the information you provide. Automated decision-making is never used - every application is reviewed and all decisions, including whether to progress your application, are made exclusively by a member of our recruitment team. Your data will be handled in accordance with our Privacy Policy and UK GDPR.

We’re #1 in our industry when it comes to our values, our culture and our people - check out Glassdoor if you don’t believe us. We offer a fantastic place to work in a great working culture and were recognised as #25 in the Top 50 places to work in the UK in 2022! We may be one of the leading budget gym chains in the UK but there's nothing budget about our investment into our people. We have retained GOLD in our investors in people award for the last 6 years and were awarded silver in wellbeing last year. We’re also recognised as a disability confident and inclusive employer which is something we are truly proud of. We have been through some great and positive change recently from our shiny new “super G” logo to our exciting digital projects and our plans are to keep being innovative, creative and agile in all that we do and we want to do that sustainably. We hire people with real passion, positivity and enthusiasm who motivate and inspire those around them. Our vision is to have a diverse, high performing, engaged workforce that love what they do! We have a brilliant team and opportunities for development and growth with support for success. We don't want to stand still, we're growing, innovating and adapting, we're with you to reach you career goals too.