Overview Join to apply for the Full Stack Engineer role at Primer. Primer is the world's first unified payment infrastructure, empowering businesses worldwide to unleash their payment potential. Merchants can control their payment stack, create unique commerce experiences, accelerate roadmaps, and increase payment success. Primer aims to make complex payments simple and intuitive. We have backing from top investors including Accel, Balderton, Iconiq, and Tencent, supporting our vision to rebuild payments and commerce from the ground up. Join us in shaping the future of payments and commerce. Note: Sponsorships or relocation packages are not offered at this time. Team and role Our Optimisation team helps merchants optimise payments KPIs, with goals to improve payment success, drive adoption, and increase expertise. The team covers fallbacks, fraud prevention, network tokenisation, and observability dashboards. You’ll report to an Engineering Manager and join a cross-functional team of backend, full-stack, and frontend engineers working with our Product team. We operate with a “you build it, you own it” ethos, including infrastructure work and self-directed testing and QA. Our tech stack includes: Python, TypeScript, React, AWS, Kubernetes and Terraform, among other technologies. What will you be doing?

Improve and optimise fallback mechanisms to ensure seamless payment processing. Enhance reliability by implementing smart routing and failover strategies. Redesign data pipelines to improve monitoring, tracking, and real-time insights. Ensure data accuracy and integrity across payment systems. Build and refine an A/B testing framework to test different payment flows. Develop if X, then Y decision-based logic to optimise transaction success rates. Enable rapid iteration and data-driven improvements in the payments experience.

What we’d love to see

Someone comfortable working across the stack, with some backend experience (Python preferred) but primarily frontend-focused. Experience with testing frameworks and writing testable, maintainable code. Ability to set goals, define success metrics, drive sprints and lead refinement sessions. In-depth understanding of the entire development process (design, development, deployment). Highly motivated self-starter who values autonomy and getting things done. Excellent verbal and written communication skills. Experience working in a fast-paced environment.

You may not like it here if

You prefer an office setting; we are remote-first. You’re uncomfortable with shifting context and navigating ambiguity. You don’t enjoy testing your code; Primer has no dedicated testers or QA.

Life at Primer We’re recognized as a top global employer, including #1 in FinTech for ‘flexibility’. We are building a culture where people can do their best work and feel proud of their impact. Our team is mission-driven, smart, and collaborative, focused on delivering exceptional products for our merchants, while also having fun along the way. We work remotely with thoughtful face-to-face time through workstations, annual company retreats, and global coworking space access. Perks and benefits include remote-first work, competitive share options, uncapped holidays (minimum 25 days), workations and company retreats, the best equipment for your role, £500 toward home office setup, a generous learning budget, and location-dependent benefits. Equal opportunity and inclusion Primer is committed to building a diverse, inclusive, and authentic workplace. We encourage you to apply even if your past experience doesn’t align with every qualification. Primer is committed to equal treatment of all current and prospective employees, regardless of background or beliefs. We adopt a zero-tolerance approach to discrimination and provide equal opportunities regardless of age, disability, sex, sexual orientation, pregnancy and maternity, race or ethnicity, religion or belief, gender identity, or marriage and civil partnership. #J-18808-Ljbffr