Senior Full-Stack Developer Next.js · React · TypeScript · AI-assisted development

Senior Full-Stack Developer
Next.js · React · TypeScript · AI-assisted development

Onlined | Chandlers Ford, Hampshire
Full-time, permanent | Hybrid: two days a week in the office
Salary dependent on experience, discussed openly and early

The opportunity

We’re looking for an experienced full-stack developer who can take a project from the first client conversation through to a fully scoped, documented and working application.

You’ll lead technical discovery, turn client requirements into comprehensive system specifications, and take ownership of the build. This includes understanding the business problem, defining how the whole system should work, estimating the development and delivering it through to launch.

You’ll work with Next.js, React and TypeScript, using Claude Code and similar tools as part of your everyday workflow. This is a hands-on senior role with real influence over our technical decisions and how we deliver projects.

About Onlined

Onlined is a digital agency based in Chandlers Ford, with around 20 years of experience in web design, development, SEO and digital marketing.

We’re a small team with long-standing client relationships and a growing portfolio of bespoke application development. You’ll work directly with the Managing Director and alongside colleagues in design, development, business analysis and project management.

You’ll see projects through from beginning to end, know the people you’re building for and have the freedom to improve how we work. We often have several client projects running at once, so balancing priorities and communicating clearly matters.

What you’ll do

Technical discovery, scoping and documentation

• Lead the technical side of client discovery meetings, asking questions to understand business processes, user needs and what the system must achieve.
• Turn those conversations into clear, comprehensive technical documentation covering the full system.
• Define functionality, user roles and permissions, user journeys, workflows, data structures, integrations and requirements for security, performance and accessibility.
• Identify gaps, assumptions, dependencies and edge cases, and work with clients and colleagues to resolve them before development.
• Produce scopes of work and technical specifications with clear acceptance criteria, so clients, developers and testers understand what will be delivered.
• Define what is included and excluded, distinguish launch requirements from future phases, and explain technical options and trade-offs.
• Break the scope into practical development phases and produce realistic estimates.
• Keep documentation up to date as decisions are made and requirements evolve.

You’ll work closely with our business analyst and project managers, but ownership of the technical specification and system design will sit with you. You should be comfortable creating the documentation yourself and taking clients through it to confirm understanding.

Development and delivery

• Own technical delivery from the agreed specification through architecture, development, testing, deployment and ongoing improvements.
• Build applications using Next.js, React and TypeScript, working across interfaces, APIs, databases and integrations.
• Set up and maintain repositories, development environments and deployment pipelines.
• Use Claude Code and other AI development tools effectively, reviewing and validating their output.
• Build security, accessibility, performance and maintainability into your work.
• Test applications against the agreed requirements and acceptance criteria.
• Review other developers’ work, help resolve technical problems and contribute to shared development standards.
• Communicate progress, risks and scope changes clearly with colleagues and clients.

You’ll develop estimates with input from the team and agree delivery plans with the Managing Director. Commercial negotiations and closing sales remain with the Managing Director.

Some existing client websites use WordPress and WooCommerce. Other team members handle their day-to-day development and maintenance, but you may occasionally help with a more complex issue or integration.

What we’re looking for

• Strong commercial experience delivering and maintaining production web applications.
• Exceptional attention to detail across technical documentation, application behaviour and interface quality, including edge cases and consistency with the agreed…