Role: Lead Full-Stack Developer

Context

Action for Happiness (AFH) is a charity on a mission to create a happier and kinder world. We turn the science of wellbeing into simple, evidence-based actions that help people feel better, feel more connected and make a positive difference to others.

Over the past decade, we’ve reached tens of millions of people worldwide through initiatives like our monthly action calendars, 10 Days of Happiness online programme, our app, Happiness Habits courses, groups and volunteer-led community programmes.

We’re now entering a new phase. Our ambitious 2026–2028 strategy focuses on simplifying and enhancing our offer, reaching new audiences, strengthening engagement and measuring our impact even more effectively.

Digital innovation is at the heart of this strategy. We want to build on the success we've had (reach of 35M+ on socials, 800k members, 250k+ using self-service digital interventions, and 500k+ joining live events). We now want to bring more technology expertise in-house, to improve what we have and build innovative new products to create a happier world.

Overview of the role

This is a senior, hands-on builder role with end-to-end responsibility for Action for Happiness’ technology and software development.

You will take ownership of:

• our existing digital systems and products
• designing and building a new, AFH-owned platform that underpins future products
• the technical design and implementation of new & innovative ‘AI-first’ digital products that help people take action to be happier.

Your skills and experience will also:

• enable us to more rapidly experiment and test new product ideas
• help us harness AI-based tools to dramatically increase speed and impact
• remove our reliance on external agencies
• ensure we build robust products that are ready for wider roll out and can be monitored, maintained and scaled-up in production.

This is not a narrow engineering role. It’s a high-autonomy, high-impact position for someone who enjoys combining technical judgement, product development and creative problem-solving. In this role you will have significant technical autonomy and the opportunity to shape the architecture, tools and development approach used across the organisation. Most importantly, you will be someone who wants to use their skills to make a positive difference in the world and help people live happier lives.

Details:

Location: Flexible / remote-friendly (UK-based preferred but not essential).

Contract: 3-year contract, with potential to review/extend.

Remuneration: Competitive and dependent on experience.
We recognise this is a senior role and can offer a strong package for the right candidate.

Time commitment: 3-5 days/week (preference for Full Time, but open to discuss).

Reporting to: CEO/Director of Action for Happiness.

What you’ll be responsible for

1. Owning AFH’s existing technology landscape

• Take overall responsibility for our digital architecture, systems and development work
• Understand, maintain and improve existing products (e.g. email/SMS-based journeys like 10 Days of Happiness and our iOS and Android apps)
• Lead the transition from our current agency-run Drupal website towards something we can own, develop and evolve in-house

2. Building a new core platform

• Design and build a new in-house platform to support:
• single sign-on / universal user accounts
• shared user identity across website, app and future products
• clearer user journeys and pathways between our various offerings
• Create a flexible foundation that supports future flagship offerings rather than one-off projects

3. Enabling rapid product experimentation

• Support rapid prototyping of new product ideas to help people take action to improve their wellbeing & happiness
• Run A/B tests and iterate based on user behaviour and feedback
• Help the organisation move from “build then hope” to “test, learn, refine”

4. Taking an AI-first approach to development

• Actively use modern AI-assisted coding and development tools to accelerate development and experimentation.
• Explore new ways of working enabled by AI (e.g. faster iteration, smaller codebases, rapid refactoring)
• Combine solid engineering principles with modern AI-assisted development.

5. Collaborating across the organisation

• Work closely with the AFH team to translate ideas into working products
• Support non-technical colleagues to understand what’s possible and what to test next
• Contribute to strategic discussions about products, users and scale

What success looks like

Within the first 12 months:

• A clear technical vision and architecture for AFH’s future platform
• Initial platform in place, including universal user login / account system
• Reduced reliance on external agencies as development moves in-house
• Faster cycles of experimentation with new product ideas regularly tested with users

Within 24 months:

• Stable and scalable technology platform supporting flagship programmes
• New digital products successfully launched and iterated based on user feedback
• Improved ability to track user actions and engagement across different AFH offerings
• Proven capability for rapid future product development and roll-out
• Increased capacity for experimentation and innovation across the organisation

Skills and experience we’re looking for

Essential

• Strong experience as a full-stack developer, comfortable working across front-end, back-end and systems
• Strong interest and experience in using AI tools to accelerate development
• Ability to design, build and maintain production systems independently
• Comfortable working with a non-technical product owner and owning technical decisions end-to-end
• Track record of developing robust and reliable products that are ready for wider roll out and can be monitored, maintained and scaled-up effectively in production
• Comfort working in ambiguous, early-stage environments
• Strong problem-solving skills and pragmatic judgement
• Interest in wellbeing, behaviour change or social impact
• Alignment with the mission and values of Action for Happiness

Desirable (but not essential)

• Experience building platforms, not just single products
• Experience with user authentication, identity or account systems
• Experience running experiments or A/B tests
• Familiarity with email, SMS or messaging-based products
• Experience working in small teams or as a solo developer

We care more about what you can build and how you think than about formal credentials.

Working style and values

We’re looking for someone who:

• enjoys responsibility and autonomy
• is calm, thoughtful, trustworthy and collaborative
• values speed and learning over perfection
• can explain technical ideas clearly to non-technical colleagues
• wants their work to make a genuine positive difference in the world

Who should apply?

Action for Happiness is committed to diversity, equity and inclusion and welcomes applications from people of all backgrounds. You can read our DEIB Policy here. If you feel excited by the role but don’t tick every box, we’d still love to hear from you. This is a rare opportunity, and we’re open to people with slightly unconventional profiles who bring the right mix of skills, judgement and motivation.