Senior Full Stack Engineer Contractor

About the Role: OnBuy is a fast-growing UK online marketplace on a mission to be the best choice for every customer, everywhere. As a Senior Full Stack Engineer, you will own engineering delivery end-to-end; from customer-facing experiences to underlying services and data systems. You will operate within a cross-functional team and be accountable for shipping high-quality, scalable solutions that directly impact GMV, seller performance, and customer experience.

What You'll Do

• Design, build, and maintain full-stack solutions across UI, APIs, and backend systems.
• Build responsive, high-performance user interfaces using modern JavaScript frameworks.
• Work across monolith and microservices architecture developing scalable Laravel / PHP services.
• Write and maintain automated tests (unit, integration, end-to-end) and optimize systems for performance and scale.

What You Bring

• Strong full stack engineering experience, owning end-to-end delivery.
• Proven backend expertise in PHP (Laravel) and strong JavaScript (ES6+) skills with modern frameworks (React/Vue/Angular).
• Experience designing and building RESTful APIs and scalable systems with MySQL and NoSQL databases.
• Experience with event-driven systems (e.g., RabbitMQ, Pub/Sub), cloud environments (GCP), Docker, and CI/CD pipelines.

Benefits

• Competitive day rate of £550 - £650 per day (Outside IR35).
• 4-month contract engagement with a fast-growing tech company.
• 100% remote work flexibility within the United Kingdom.