Senior Backend Developer (PHP)

Job Description

3 reasons you should join our team

• You will work on systems that cannot go down. You design and maintain a high-availability platform that processes millions of secure transactions every day around the globe
• You will go deep on backend craft. From creating and optimising microservices to levelling up database performance, you help build a backend known for accuracy, security, and long-term reliability
• You will join a sharp and friendly engineering team. You collaborate with more than 30 experienced engineers, ship in agile teams, share knowledge, and solve complex payment challenges that actually matter

Our offices are located in Delft, near Rotterdam. If you do not know Delft yet, it is one of the most loved cities among engineers, with beautiful canal-lined streets, good beers, a strong tech vibe, reasonable housing prices, a walkable centre that keeps life easy, and public transport that gets you anywhere fast.

Build the backbone of global e-commerce

What started as five people, a small office, and some orange nerf guns has grown into one of Europe’s fastest-growing fintechs. With 150+ colleagues, offices in Delft, Berlin, and London, and Worldline as our partner, we’ve got the perfect mix: the power of a global leader with the energy of a scale-up. At OPP, we build the technology that powers the next generation of e-commerce. From eBay Kleinanzeigen to IKEA, millions of users rely on our systems every day. We don’t just process payments, we enable platforms to accept, hold, and disburse funds securely. 24/7.

As Senior Backend Developer, you contribute both strategically and hands-on. You work on the core of our platform: strengthening critical services, introducing cleaner architectures, and preparing our systems for new payment flows across Europe. You help us make smart choices about performance, reliability, and security, and you are comfortable dealing with the real-world complexity that comes with scale. With traffic rising across all regions, you help us stay fast and reliable under pressure and you guide teammates through complex engineering trade-offs. You do all this as part of one of our agile Scrum teams focused on in-platform payments, onboarding, and core product innovation. You work with developers who know payments inside out and who tend to stay, because the work is meaningful and the team is strong. Our tech office sits in the city centre of Delft, a dedicated dev-only space for deep work with plenty of places nearby to grab a coffee or clear your head.

Some of the projects you’ll be part of

• Build new in-platform payment flows that move money in ways traditional e-commerce never had to.
• Level up onboarding and compliance, making it faster for users and stricter where it counts.
• Break big systems into clean microservices that stay fast when traffic hits across Europe and the UK.
• Create the APIs and tools platforms need to grow without waiting on us.

Our tech stack

PHP, Laravel, Symfony, MySQL, Redis, Docker, Kubernetes, CI/CD.

Job Requirements

Your track record tells us

• You have deep experience with PHP and MySQL and know how to build stable, well-performing systems.
• You can build and ship at a senior level in Laravel or Symfony.
• You have worked on high-traffic platforms or microservice architectures.
• CI/CD, Docker, Kubernetes, caching, queues, optimization, scalability, and performance tuning are part of your everyday toolkit. If you have experience with Redis or scalable microservices, even better.
• You can communicate complex technical topics clearly, also to people outside engineering.
• You are currently based around our Delft office.

Our offer

• An all-in annual salary up to €100.000
• A modern, flexible workplace with hybrid working.
• 24 vacation days and 2 Diversity Days⚡.
• 12-month contract with the possibility of extension and finally a permanent contract.
• The tools you need: a MacBook, €1000 for your home office setup, and NS Business Card.
• An attractive bike plan if you work 24 hours or more.
• A developers-only office at Lange Geer 26, within walking distance of our sales and product teams in the heart of Delft.
• A great work atmosphere with catered lunches and regular team drinks.

From contact to contract

Inclusion matters at OPP

At OPP, we believe that different perspectives make better decisions. We are a diverse team and value you for who you are, not just your CV, so we encourage you to apply even if you don't check every box. We are committed to building an inclusive environment where everyone can make an impact. If you need any adjustments or accommodations to participate fully in our recruitment process, please let us know so we can support you.

Want to know more about our projects?

Let’s talk! We’ll tell you everything you need to know. Send your CV or get in touch with our tech recruiter Georgios at

[email protected] .

Hiring for this position is ongoing, so you may have seen this vacancy before. We are continuously expanding our engineering team and are always interested in connecting with ambitious experienced professionals.

👋 Hey! I’m Mike , CTO at OPP and your hiring manager for this role.

“Did you know that our APIs are called millions of times a day? Help us keep our platform lightning fast - let’s meet!”