Sr Software Engineer, Ads Auctions & Marketplace Optimization

What does the team work on?

Roku is the No. 1 TV streaming platform in the US, Canada and Mexico, with more than 100 million active accounts. Every ad impression across that platform has to be cleared and priced in real time — that is what the Ads Auctions and Marketplace Optimization team does. We build the auction mechanics, the pricing and pacing logic, and the low-latency systems that run them, balancing outcomes for advertisers, publishers, viewers, and Roku on every request. We are growing the team in Cambridge, which is becoming its largest hub, alongside colleagues in Amsterdam, Austin, San Jose, Ukraine and Uruguay — so you would be shaping how the UK side of this team works rather than inheriting it.

What is the role?

You will build the systems that apply mathematical and algorithmic rigour to optimise across multiple objectives, deciding which ads get served, in which placements, and when. The work spans auction mechanics, optimisation, the output of predictive ML models, and the real-time infrastructure underneath, mostly in Java on the JVM. It is hands-on and senior in scope: expect to move between whiteboard-level design and production code in the same week, and to own problems from framing through rollout. You will work directly with the hiring manager and a small group of senior engineers, in codebases shared with other ads engineers, on problems where your decisions are visible in revenue. You will optimise for second-order effects in a marketplace where participants react to each other, and to us, in real time. We are looking for people who are enthusiastic about solving these kinds of problems.

How will I use AI at Roku?

At Roku, we don't just use AI, we work with it. AI agents and smart tools help power drafts, analysis, and repetitive workflows, while our people bring direction, judgment, and accountability. We're looking for curious, adaptable builders who can show how they've used AI or automation to move faster, raise the bar, and scale their impact.

We value your AI skills if you have built fluency across the agentic engineering toolchain — coding harnesses like Claude Code or Cursor, MCP servers, custom skills, or agent frameworks. And you can describe projects where you shipped real work with these tools. You know how to drive an agent, verify its output, and ramp on an unfamiliar codebase with an agent helping you.

What are the responsibilities of the role?

• Design and build components of Roku's real-time ad auction and marketplace systems
• Own the multi-objective optimisation at the core of the auction, balancing what advertisers, publishers, viewers, and Roku each want from the same impression
• Own development work end to end, from framing the problem through production rollout
• Build and operate JVM services where latency and reliability are product requirements, not stretch goals
• Use probability, statistics and experimentation to test changes before and after launch
• Work with AI tooling as a normal part of how you design, build, test and review
• Explain technical trade-offs clearly to engineering and cross-functional partners

What experience would help someone be successful in this role at Roku?

• Around six or more years building production software, with strong systems judgement
• Production experience in Java or another JVM language, or depth in a comparable statically typed language such as C#, C++ or Go, and the appetite to ramp on Java
• Comfort designing and operating distributed systems at scale and low latency
• A solid grounding in maths, algorithms, probability and statistics as applied to real systems
• Demonstrated AI and agentic-tooling fluency, as described above
• Ad tech, auctions or marketplace experience is preferred, and we move quickly for candidates who have it
• Comparable experience on mathematically rigorous or optimisation-heavy problems in another domain is an acceptable alternative