Senior Java Developer - DSP (PurchaseLoop)

About LoopMe

LoopMe is an AI company solving one of advertising's hardest problems: making brand advertising actually measurable — and making it perform. Our platform runs patented machine learning models across billions of consumer signals in real time, optimising campaigns toward outcomes like purchase intent, brand lift, and foot traffic rather than proxy metrics like clicks. The result is 2–5x better performance than industry benchmarks, at scale.

We operate a high-load programmatic infrastructure — processing millions of ad requests per second with sub-200ms response times globally. This isn't a layer on top of someone else's stack; it's built from the ground up, in-house, by the team you'd be joining. Founded in 2012 and headquartered in London, we now have 400+ people across 19 cities and have sustained 40% revenue CAGR since 2018. The engineering problems here are real, the ownership is genuine, and the scale is significant.

The opportunity

You'll join the PurchaseLoop DSP engineering team, working on a high-load ad-serving system that processes over 2 million requests per second at under 50ms response times. You'll build and optimise the core Java infrastructure that powers real-time bidding for global advertisers, working closely with data science to bring complex targeting algorithms to production.

What you'll do

• Own feature development and performance optimisation for our Java ad-serving application at production scale
• Implement complex targeting algorithms from the data science team into the core ad-serving flow
• Build backend services supporting BI ad-hoc queries across high-volume data sets
• Drive strong testing practices across unit and integration test coverage for critical systems
• Partner with a distributed engineering team across Ukraine, Poland, and the UK to ship features under Agile methodology
• Mentor mid-level backend engineers, helping to raise technical standards across the team

What you'll bring

Essential:

• 5+ years of backend Java development, including Java 17+ with Spring Boot and Gradle
• Demonstrable experience designing and implementing REST APIs in production environments
• Strong SQL skills with PostgreSQL, including schema migration management
• Experience building and operating microservices architectures at scale
• Production experience on GCP or a comparable cloud platform

Nice to have:

• Familiarity with GraphQL on the consumer or provider side
• OpenRTB knowledge or broader adtech domain experience
• Experience with Kubernetes or GKE
• Exposure to event-driven systems
• Use of AI-assisted coding tools such as Claude Code or GitHub Copilot

What we offer

• Flexible working schedule
• 1 month work-from-anywhere
• Annual performance bonus
• English classes
• LoopMe Gives Back
• Learning & development support