About mediaROI
mediaROI is a Unified Marketing Measurement SaaS platform that enables advertisers to steer the real impact of their marketing investments by combining MMM, attribution and incrementality, with an automated, AI-driven approach.
We work with French and international advertisers across Europe, with a clear ambition: moving from one-off studies to continuous, decision-grade measurement. We are an AI-native startup, and it shows both in our product and in the way we work every day.
Your role
Reporting directly to the CTO, within a team of 8, you own the technical quality of our modelling stack. You are the company’s data science referent: you take ownership of your topics, you ship them, and you stand behind them.
Your missions
1. Evolve the model and the platform
- Take ownership of our Meridian-based MMM engine and push it forward, including modifying Meridian itself when needed.
- Work on our unified measurement framework (MMM, attribution, incrementality) and contribute to its integration into the platform.
- Improve the training part of our web app, both product-wise and technically, to better support online model training.
2. Ensure the quality of client models
- Drive data preparation (structuring, validation, QA) and model training on your client projects, in partnership with our marketing scientists: you validate, debug and own the final quality of the models under your responsibility.
- Guarantee the quality, consistency and credibility of the delivered outputs.
- Occasionally support clients on technical topics: methodology, interpretation, advanced questions.
Who we are looking for
We are looking for a builder: someone who designs, builds and ships end to end, and takes responsibility for what they produce. You take on a substantial scope, carry it through to production, and work autonomously, making most of the decisions on your own.
Two criteria matter as much to us as MMM expertise:
- You have built products, and you can show it. Applications, internal tools, side projects, open source contributions: we want to see what you have designed and shipped yourself, and understand the choices you made.
- You code with AI every day. Claude, Cursor, ChatGPT or equivalent are part of your daily practice, not an occasional assist. You know how to frame a problem, drive these tools and ship far faster thanks to them.
Experience
- Significant experience in MMM / marketing measurement (consultancy, advertiser, tech).
- You have already built MMMs end to end for clients, and you are comfortable debugging a model that does not converge as expected.
- Hands-on experience with Meridian is a strong plus; otherwise LightweightMMM, Robyn or PyMC.
Technical skills
- Solid foundations in Bayesian modelling (prior selection, MCMC convergence diagnostics) and time series: you will work on our unified MMM / attribution / incrementality methodology.
- Strong command of MMM concepts (adstock, saturation, baseline, halo effects).
- Comfortable reading and modifying an open source Python codebase such as Meridian.
- Python.
Business & soft skills
- Strong understanding of marketing and media challenges.
- Clear and fluid communication: you can explain complex topics simply, in writing and out loud, to non-technical people.
- Analytical rigour and critical thinking.
- Autonomy, proactivity, sense of ownership.
- Fluent French and English: our teams work in French and our clients are all over Europe.
What this role is not
For the sake of transparency, and to avoid any misunderstanding:
- It is not an audit or methodological consulting role: mediaROI advises its clients, but within the tech team your job is to build the models and the product that make those recommendations possible.
- It is not a research role: the topics are demanding, but they serve a product delivered to clients, on deadlines.
- It is not about operating an existing pipeline: the model is meant to be developed in depth.
- It is not a management position in the short term: the team is small and the role is fully hands-on.
Why join us
- Join a fast-growing startup with a culture built on freedom and responsibility.
- Build an AI-native SaaS product in a rapidly expanding market.
- Have a direct impact on the product, the methodology and the strategy.
- Work with major accounts in France and across Europe (retail, e-commerce, FMCG).
Package
- Attractive package: fixed salary + BSPCE (stock options).
- Equipment provided (MacBook Pro or equivalent).
- Health insurance, meal vouchers (Swile), 50% public transport.
- Office at Station F, full remote possible, regular presence in Paris preferred.