Backend Software Engineer

Job Description

We’re looking for a Backend Software Engineer 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 lead the transformation of the advertising industry by proving that effective advertising and user privacy can coexist.

We are the leading Neuro-Contextual Advertising Company, combining advanced 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, delivers a deep, human-like understanding of context, emotion, and intent. This allows brands to connect with audiences at the right moment across the open web and Connected TV, without relying on cookies or user tracking.

Founded in 2014 by two ex-Googlers, Seedtag has grown to more than 700 Seedtaggers across 17 countries, backed by €250M in funding, and is now operating at scale as a global ad-tech leader.

If you are excited about solving complex engineering challenges, building AI-driven systems at massive scale, and shaping the future of privacy-first advertising, this is the place for you.

Your Challenge

As a Backend Software Engineer, you will:

You will be responsible for building and improving services which will have a direct impact on our client’s advertising KPIs and operational efficiency.
You will work on end-to-end projects, taking solutions from concept to production, and focusing on creating scalable, efficient, and impactful solutions.
As a member of our engineering team, you will develop new projects mainly on the backend side, but sometimes, you’ll support particular frontend needs. You’ll be in charge of the CI/CD, dimensioning production instances and scaling.
You’ll provide an analytical mindset, being able to go to our data lake in order to validate your own hypothesis and try to get your own conclusions to discuss afterwards with the team.
Collaborating closely with our cross-functional teams, your work will be aligned with business goals and drive the practical application of your solutions.

Our Core Values

Outcome over Output

We focus on impact rather than volume. Success is measured by the value we create for users and customers, not by features shipped or lines of code written.

Failure Is Allowed, Learning Is a Must

Innovation requires experimentation. We test early, iterate often, and treat mistakes as opportunities to learn and improve.

We Are All Scouts

We believe in leaving things better than we found them. Ownership, responsibility, and proactive improvement are core to how we work every day.

We Are Data-Driven

Data guides our decisions. We rely on measurable insights to optimize our systems, models, and processes and to continuously improve outcomes.

Tech Stack

We operate at a massive scale, supporting up to 120k requests per second, with machine learning models responding in under 10 milliseconds, and processing 20 TB of data daily with low-latency access.

Our core stack includes:

Languages: Python, Go, TypeScript, Scala
Infrastructure & Cloud: Kubernetes, Google Cloud Platform (GCP), AWS
Streaming & Messaging: Kafka, Kinesis
Data & Storage: Datalakes, GCS, Redis, Druid, MongoDB
Architecture: 100+ microservices, DevOps-oriented, continuous deployment

What You’ll Need to Succeed

You bring 3-5 years of experience into backend software engineering, from the conceptualization of the problem to the deployment in production and validation that works.
You have collaborated on some front-end projects even if it’s not your strongest skill.
You are a DevOps-oriented engineer who is responsible for the CI/CD of the services you build, you understand how to do the sizing of production deployment and how to troubleshoot if something is not working as expected.
You deeply understand the problem you are trying to solve. You measure the outcome of the development you do.
You have worked in related disciplines which can include Data engineering pipelines, infrastructure provisioning or deployment of ML models in production.

Why Join Seedtag?

Growth & Opportunity: Join at a key moment of scale with real ownership, global projects, and internal mobility.
Flexibility: Work 100% remotely or in a hybrid setup. We trust you to choose what works best for you.
(Please note that while we are remote-first, contracts can only be offered in countries where we have legal entities: Spain, Italy, the UK, Belgium, the Netherlands, France, and Germany.)
Learning & Development: Access to online learning, continuous training, and optional English or Spanish group classes.
Inclusive Culture: A supportive environment where growth, trust, and well-being are part of everyday work.
Fun & Connection: Team activities, company offsites, and regular opportunities to connect beyond work.

Additional Perks

Flexible benefits plan including restaurant, transportation, and kindergarten vouchers
Health insurance coverage
Gympass access to wellness and fitness programs
Seedsave Program with exclusive discounts
Home office setup budget of up to €1,000
MacBook Pro M3
Paid trips to our HQ in Madrid to work face-to-face with your squad

Ready to Join the Seedtag Adventure?

At Seedtag, we foster an inclusive environment where everyone can thrive. We welcome diverse perspectives, as they fuel our innovation and growth. If you require any accommodations during the hiring process, please let us know and we will ensure a positive and accessible experience.