Senior Software Engineer, Backend

An Introduction to Primer

Primer is the world's first unified payment infrastructure, founded by former leaders of Braintree and PayPal. We unify fragmented payment and finance systems into a single, intelligent platform, automating the entire payments lifecycle from acceptance and orchestration to reconciliation, FX, and financial operations.

Trusted by leading merchants worldwide, we give finance, payments, and engineering teams the tools to move faster, reduce complexity, and unlock growth. Our open, modular platform connects to 150+ services across the payments ecosystem, while our expanding CFO product suite brings unified reconciliation, FX management, and financial visibility across markets and currencies.

Backed by Accel, Balderton, ICONIQ, and Tencent, we're setting a new standard for how the world moves money.

Which team will you be joining?

Our Partners team is reimagining how we enable third party payment service providers to unlock the power of Primer’s unified payment infrastructure, providing a scalable and flexible platform for growth.

Reporting to an Engineering Manager, you’ll join a team of backend, frontend and mobile engineers all working together alongside our Product team.

The team adopts a ‘you build it, you own it’ approach, working with infrastructure, doing their own testing and QA.

Our tech stack includes: Python, Typescript, React, Swift, Kotlin, AWS, Kubernetes and Terraform, amongst lots of other things.

🔍 What will you be doing?

• Leading the design and implementation of core backend services for high performance, complex distributed systems
• Taking ownership of key technology decisions, building for scale and optimising for output
• Driving and using modern development practices such as BDD and TDD would be highly beneficial
• Creating clear, modern, well tested code
• Collaborating across teams in a product-driven environment
• Conducting code reviews and continuously look at ways of improving our ways of working
• Creating detailed internal documentation for the projects you work on

👀 What we’d love to see

• In-depth understanding of the entire development process (design, development and deployment)
• Knowledge of building developer frameworks and workflows, allowing both customers and third-parties to integrate as seamlessly as possible
• Experience in Python is advantageous (it's what we use!) but we have had success hiring engineers of any technical background and understand that people can adapt
• Highly motivated self-starter who values autonomy and getting things done
• Excellent verbal and written communication skills
• Payments knowledge, always looking for ways to optimise our merchant developer experience
• You will need to be based in: Poland, Portugal, Hungary, Romania or South Africa.

🚫 You may not like it here if

• You enjoy working in an office-setting, we are remote-first and always will be!
• You are not comfortable with shifting context and navigating ambiguity
• You don’t enjoy testing your code, we have no testers or QA’s here at Primer

✅ Our interview process

• 30 minute call with a Talent Partner
• 60 minute interview with an Engineering Manager
• 90 minute coding interview in Python
• 90 minute system design interview
• 60 minute final stage values-alignment interview

What’s the culture like at Primer?

We’ve been recognised as a top global employer, #1 in FinTech for ‘flexibility’!

Our 2025 Product Showcase

We’re building a culture where people can come and do their best work and enjoy it. We want our people to be proud of the impact that they have at Primer, and of the work that they are doing. You will be working with a team of people who are mission-driven, smart, and reflective, and who are invested in building exceptional products and delivering success for our merchants (and we also know how to have fun along the way).

We work remotely. We believe that building a successful, profitable company goes beyond proximity. We invest in our relationships with each other through great remote working practices and thoughtfully designed face-to-face time together. Our heads-together time comes in the form of workstations, our annual company retreat, and co-working space access worldwide.

Finally, let’s go ahead and say it. The work that we do is challenging. Startups are a challenge, building category defining products is a challenge. You should be prepared for a challenge at Primer. But, there’s a big difference between a challenge and a struggle. The key difference is that the right challenge comes with the right support structures, an acceptance that not everything always goes to plan, a collaborative environment, and a great team around you. It’s never a challenge that you will face alone.

Our benefits

🌍 We are fully remote and globally distributed; and have been since day one

💰 Competitive share options

🌴 Uncapped holiday, with 25 days minimum to be taken

🗣️ Co-working space access

📅 Workations & Company Retreat

💻 The best equipment for your role

🏠 £500 towards your home office setup

🔎 Generous learning budget

🏥 Private Medical Insurance

📈 A broad set of additional perks and benefits ( depending on location)

Don’t meet every single requirement?

At Primer, we’re dedicated to building a diverse, inclusive, and authentic workplace. If you’re excited about this role but your past experience doesn’t align perfectly with every qualification in the job description, we encourage you to apply. You may be the right candidate for this or other roles. Primer is committed to the equal treatment of all current and prospective employees, regardless of background or beliefs.

Primer adopts a zero-tolerance approach to discrimination. We are committed to providing equal opportunities to all current and prospective employees regardless of age, disability, sex, sexual orientation, pregnancy and maternity, race or ethnicity, religion or belief, gender identity, or marriage and civil partnership.