Backend Software Engineer - AdExchange in London

We’re looking for a Backend Software Engineer - AdExchange to join our tech team and help build the future of neuro-contextual advertising at global scale.

Who We Are

At Seedtag, our mission is to transform advertising by proving that effectiveness and user privacy can truly coexist. As the leading Neuro-Contextual Advertising Company, we combine Artificial Intelligence, Natural Language Processing, Computer Vision, and neuroscience to understand not only what content is about, but how it makes people feel and what they intend to do next. Our proprietary AI, Liz, enables brands to connect with audiences across the open web and Connected TV without cookies or user tracking. Founded in 2014 by two ex-Googlers, Seedtag has grown to 700+ Seedtaggers in 17 countries, backed by €250M in funding, and operates today as a global ad‑tech leader.

Your Challenge

• Architecting, refining and developing the backend services that power our AdExchange.
• Optimising the high-throughput real-time bidding systems where you’ll balance ultra-low latency requirements with cost-efficiency and reliability, ensuring our infrastructure scales sustainably.
• Integrating new demand partners, owning the full lifecycle from capacity planning and endpoint configuration to traffic shaping and performance validation.
• Designing pricing and auction mechanics, including bid flooring systems and dynamic margin calculations, serving machine learning models in real-time to optimise revenue.
• Building event pipelines and reporting integrations that enable data teams to analyse performance, debug issues, and feed AI models.
• Working on end-to-end projects from concept to production, making technical decisions, managing priorities, and communicating effectively with stakeholders across the company.
• Collaborating closely with cross-functional teams with a data-driven analytical mindset, validating hypotheses with real data and aligning engineering work with business goals.

This is a high-impact challenge that will shape the future of Seedtag. If you are up to the challenge and want to be a part of a talented and passionate team, we encourage you to apply for this position.

Our Core Values

• Outcome over Output: We measure success by impact and value, not by volume of features or lines of code.
• Failure Is Allowed, Learning Is a Must: Experimentation is key to innovation. We test early, iterate often, and learn fast.
• We Are All Scouts: We take ownership and leave things better than we found them.
• We Are Data-Driven: Data informs our decisions and helps us continuously improve our systems and results.

Tech Stack

We use Go, Typescript, Python, Mongo, Redis, Google Cloud, Kafka… We craft high-throughput micro-services, APIs, data pipelines, async message queues… We breathe DevOps, love Kanbans, Pair Programming, Peer Reviews, Continuous Discovery, Delivery and Integration. We are on Slack, Notion, JIRA, and GitHub.

What You’ll Need To Succeed

• You have a deep understanding of back-end development.
• You have at least 5 years of demonstrable experience working in software engineering, with a focus on building back-end systems.
• You have experience using it to build scalable, high-performance systems.
• You care about producing maintainable code over time using good programming practices.
• You have experience applying programming patterns.
• You have experience with high-throughput systems and distributed architectures.
• You are comfortable working with systems that handle large amounts of data and have experience building systems that scale to meet demand.
• AI-Augmented Productivity: You embrace AI tools (GitHub Copilot, Claude code, LLMs, etc.) as a fundamental part of your daily workflow.
• You understand how to leverage these tools to speed up boilerplate coding, debugging, and learning, allowing you to focus on high-level architecture and complex problem-solving.
• You are a big-picture thinker who can see the forest and the trees.
• You have a strong understanding of the technical and business requirements of the projects you work on, and you can think strategically to ensure that your work aligns with the goals of the company.
• You are a problem solver who loves a good challenge.
• You are energized by tackling complex technical problems and figuring out creative solutions.
• You are a continuous learner who is passionate about your craft.
• You are committed to staying up-to-date with the latest developments in back-end engineering and are always looking for ways to improve your skills and knowledge.
• You are a strong communicator who can work effectively in a team.
• You are comfortable working collaboratively with others, and you are able to effectively communicate complex technical concepts to both technical and non-technical stakeholders.

If you possess these qualities and are excited about the opportunity to work on challenging, high‑impact projects with a talented and passionate team, we encourage you to apply for this position.

Why Join Seedtag?

• A key moment of growth with real ownership and global impact.
• Flexible work model with 100% remote or hybrid options. (Remote contracts available in Spain, Italy, UK, Belgium, Netherlands, France, and Germany.)
• Continuous learning through a learning platform and optional language classes.
• A supportive, trust‑based culture that values well‑being.
• Team activities, offsites, and opportunities to connect beyond work.

Additional Perks

• Home office setup budget up to €1,000
• Paid trips to our HQ in Madrid
• MacBook Pro M3

Ready to Join the Seedtag Adventure? At Seedtag, we create an environment where everyone can thrive. If you need accommodations during the hiring process, let us know and we’ll ensure a positive experience. Send us your CV and let’s build the future of neuro-contextual advertising together.