Senior Full-Stack Developer, UK-based

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 work on modern ecommerce solutions used by well-known companies, shaping their systems from initial code to long-term maintenance, within an international and growing team.

Joining IONA means becoming part of a global team of over 50 professionals delivering next-generation commerce solutions for clients like Marimekko, Lappset, Vaisala, and Berner. We utilize modern, API-first, and microservices-based solutions and are a MACH -certified partner. Our team operates from Finland, the UK, and the Philippines, focusing on continuous learning, teamwork, and professionalism.

As a Senior Full-Stack Developer, you will work closely with clients in a consultative capacity, providing technical leadership and expertise. Your main responsibilities include contributing to code and architecture, owning applications from concept to deployment and maintenance, and ensuring quality, performance, and security of our solutions.

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, and ensuring code quality through CI/CD pipelines
• Troubleshooting issues across environments, platforms, and cloud architectures
• Designing and implementing integrations between internal systems, third-party services, and client platforms
• Mentoring and reviewing code of other developers for best practices, performance, and security compliance

You are a hands-on senior developer with a big-picture mindset. You can build practical, business-driven solutions without compromising on technical quality. Strong communication skills are essential for working with both technical teams and client stakeholders.

You might be the person we're looking for if you have:

• Senior-level experience in programming, including modern API-based SaaS solutions and developing responsive websites
• A solid understanding of the full software development lifecycle
• Experience with headless ecommerce platforms, especially commercetools
• Experience with headless CMSs (Contentful, Sanity, ContentStack, etc.)
• Expertise in JavaScript technologies (Next.js / React / Node), SaaS services, and major cloud platforms (AWS, Azure, GCP)
• Experience with CI/CD workflows, automated testing, and version control
• Understanding of integrations, APIs, and data pipelines in cloud ecosystems
• Excellent communication skills in English, capable of explaining technical concepts to diverse audiences
• Experience working with cross-functional teams including designers and product managers

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 integrations (payment gateways, ERP, marketing automation)

What's in it for you?

At IONA, we value continuous improvement, integrity, and professionalism. We foster a supportive environment emphasizing teamwork, curiosity, and milestone celebrations.

We embrace diversity and are committed to equal employment opportunities. Our team members come from varied backgrounds, speak multiple languages, and have different gender identities, sexual orientations, and abilities. We encourage candidates from all backgrounds to apply.