Principal Machine Learning Engineer

Job description

WELCOME TO OLX

At OLX, we work together to build a more sustainable world through trade.

We make it safe, smart, and convenient to buy and sell cars, find housing, get jobs, buy and sell household goods, and more. Our colleagues around the world help to serve millions of people around the world every month, through its well-loved consumer brands including OLX, Otodom, AutoTrader, Property24.

Join OLX and see how far you can go.

JOIN OLX SEARCH PLATFORM AI TEAM

We’re on a mission to transform how millions of people discover and connect with what they need most - across Motors, Real Estate, Jobs, Services, and Goods. To achieve this, we’re building a new Search AI Platform that will power intelligent, personalized, and scalable search experiences across all OLX customer units.

This initiative is sponsored directly by our CTO and represents a strategic leap for OLX: a new cross-functional team built from the ground up, bringing together machine learning engineers, data scientists, SREs, and platform engineers. Together, we’re redefining how search intelligence is built, shared, and scaled across our global ecosystem.

As the Principal Search Machine Learning Engineer, you’ll be the technical guiding force behind this transformation. You’ll work alongside our Principal Search Engineer to shape the architecture, mentor the team, and deliver solutions that bring measurable business and user impact. You’ll have full ownership to explore, experiment, and push boundaries - from prototyping new search models to deploying them at scale.

You’ll also play a key role in growing OLX’s data science practice, mentoring peers, and shaping how AI is applied across the company. This is a hands-on leadership opportunity where you’ll see your ideas move from research to production and into the hands of millions of users.

What you will be doing:

• Shape the future of AI-powered search across all OLX verticals. You’ll drive the technical vision, guide a multidisciplinary team, and ensure our Search AI Platform becomes a foundation for scalable, intelligent discovery experiences for millions of users.
• Lead the design and evolution of OLX’s Search AI Platform, developing LLM- and GenAI-based systems that power discovery and relevance across Motors, Real Estate, Jobs, and Goods.
• Partner with the Principal Search Engineer to define and implement a unified technical strategy for search, ranking, and retrieval at scale.
• Guide a cross-functional team of ML engineers, data scientists, and platform engineers, fostering technical excellence, experimentation, and rapid iteration.
• Prototype, evaluate, and productionize new ML models, including embedding-based retrieval, personalization, and relevance optimization.
• Collaborate with product and analytics teams to define success metrics, integrate with A/B testing pipelines, and measure real customer impact.
• Mentor and inspire data scientists and ML engineers across OLX’s global hubs, sharing best practices and shaping the future of applied ML at scale.
• Stay hands-on, driving implementation in Python and AWS while exploring state-of-the-art advances in LLMs, GenAI, and search infrastructure.
• Promote a culture of learning and innovation, helping the team iterate fast, fail fast, and learn continuously.

What are we looking for:

• Based in Portugal, with the ability to collaborate across global teams.
• Strategic and hands-on technical leader who thrives at the intersection of machine learning, large-scale systems, and product impact.
• Deep expertise in search and relevance, including ranking models, retrieval systems, and modern representation learning (e.g., embeddings, transformers).
• Proven experience designing and productionizing ML solutions at scale in real-world environments.
• Strong background in Generative AI and LLMs, with an understanding of their application to search and content understanding.
• Ability to inspire and lead cross-functional initiatives, aligning multiple teams toward shared technical outcomes.
• Proficient in Python and familiar with at least one other programming language (e.g., Kotlin, Java); experienced with ML frameworks such as TensorFlow or PyTorch.
• Solid understanding of data pipelines, experimentation frameworks, and distributed systems in cloud environments (preferably AWS).
• Exceptional analytical, communication, and stakeholder management skills, capable of translating complex ideas into actionable solutions.
• Passion for building systems that connect millions of users to what matters most, through better search, relevance, and personalization.

Nice to have:

• Experience with cloud-based tools for production use (e.g., AWS Athena, AWS Sagemaker, AWS Spectrum, AWS Kinesis) or equivalent.
• Experience building large-scale batch and real-time data pipelines with open source data processing frameworks like Spark.
• Experience with platforms for programmatically authoring, scheduling and monitoring workflows (e.g. Apache Airflow).
• Experience driving initiatives such as Tech Radar for Data Science and interacting with external groups (e.g. Amazon ML Solutions Lab or similar) to formulate and progress the Data Science Tech agenda

What we offer:

• Permanent contract
• Salary + annual bonus up to 25% of your annual gross salary
• Work with and impact all OLX services in Europe
• Train and conference budget and free access to Udemy courses
• Health insurance and life insurance
• MacBook Pro along with the necessary accessories to make your work comfortable
• 100% remote work (and the possibility to work from our offices in Lisbon)

Diversity, Equity and Inclusion at OLX

OLX values diversity and welcomes applicants of all races, ethnicities, disabilities, ages, genders, sexual orientations, religions, backgrounds, and experiences to apply. If this role excites you, we encourage you to apply, even if you don’t meet all the requirements - you may be just the right fit for this or other opportunities with us!

OLX will process your personal data to assess your fit for the applied position. You may optionally consent to store your data for up to 12 months after the application process for consideration in future OLX roles. For more details on how your application data will be processed please check our Privacy Statement.

We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.