We are looking for an experienced full-stack developer to join us as a Senior Full-stack Developer based in the UK. With us, you’ll get your hands dirty with modern ecommerce solutions used by well-known companies, shaping how they work from the first line of code to long-term maintenance, all while working in an international and growing team. About IONA When you join IONA, you'll become part of a global team of over 50 professionals collaborating to deliver next-generation commerce solutions for clients like Marimekko, Lappset, Vaisala, and Berner. We leverage modern, API-first, and microservices-based solutions and are proud to be a MACH-certified partner. Our team operates from Finland, the UK, and the Philippines, and we're focused on continuous learning, teamwork, and professionalism. What is this role like? As a Senior Full-Stack Developer, you'll work closely with clients in a consultative role, providing technical leadership and expertise. Your primary responsibility is to actively contribute to the code and architecture, taking ownership of the applications you help build from initial concept through to deployment and maintenance. You'll also be a key contributor, responsible for the quality, performance, and security of the solutions we deliver. Key responsibilities include: • Designing, developing, and implementing applications based on specifications for new projects • Maintaining and improving existing applications • Writing functionality and automated tests, debugging code, and ensuring code quality through CI/CD pipelines • Troubleshooting issues across multiple environments, platforms, and cloud architectures • Designing and implementing integrations between internal systems, third-party services, and client platforms • Mentoring and training other developers, and reviewing their code for best practices, performance, and security compliance What would make you a great fit? You're a hands-on senior developer who also thinks about the big picture. We're looking for someone with the ability to build practical, business-driven solutions without compromising on technical quality. Your communication skills will be key as you work closely with both the technical team and client stakeholders. You might be the person we're looking for if you have: Senior-level experience in programming, including experience with modern API-based SaaS solutions and developing responsive websites • A solid understanding of the full software development lifecycle • Experience with headless ecommerce and platforms, especially commercetools is a big plus • Experience with headless CMSs (Contentful, Sanity, ContentStack, etc) • Strong expertise in JavaScript technologies (Next.js / React / Node), SaaS services, and major cloud platforms (AWS, Azure, GCP) • Experience with CI/CD workflows, automated testing frameworks, and version control systems • Understanding of integrations, APIs, and data pipelines within cloud-based ecosystems. • Excellent communication skills in both written and spoken English, with the ability to present technical concepts to both technical and non-technical audiences • Experience collaborating with cross-functional teams, including designers, product managers, and other developers Extra points if you have: • Knowledge of application and cloud security practices • Skills or interest in project management, UX design, or quality assurance • Experience with advanced ecommerce-specific integrations (e.g., payment gateways, ERP systems, marketing automation) What's in it for you? At IONA, we value continuous improvement and acting with integrity and professionalism in everything we do. We drive our projects with commitment and curiosity, always pushing ourselves to do better. Our supportive environment emphasises teamwork and looking out for one another as we tackle challenges and celebrate milestones together. We embrace diversity and are committed to equal employment opportunities. Our people come from varied backgrounds, speak various languages, and have different gender identities, sexual orientations, and abilities. We encourage candidates from different backgrounds to join our team.